diff --git a/builtin/game/register.lua b/builtin/game/register.lua
index 4ecf6ec71..3e11c7e20 100644
--- a/builtin/game/register.lua
+++ b/builtin/game/register.lua
@@ -442,6 +442,11 @@ local function make_registration_wrap(reg_fn_name, clear_fn_name)
 
 	local orig_reg_fn = core[reg_fn_name]
 	core[reg_fn_name] = function(def)
+		if def.name ~= nil then
+			if list[def.name] then
+				error("Attempt to register already registered element - '" .. def.name .. "'", 2)
+			end
+		end
 		local retval = orig_reg_fn(def)
 		if retval ~= nil then
 			if def.name ~= nil then
@@ -464,7 +469,28 @@ local function make_registration_wrap(reg_fn_name, clear_fn_name)
 	return list
 end
 
-local function make_wrap_deregistration(reg_fn, clear_fn, list)
+local function make_wrap_override_deregistration(reg_fn, clear_fn, list)
+	local override = function (key, redef)
+		if type(key) ~= "string" then
+			error("key is not a string", 2)
+		end
+		local def = list[key]
+		if not def then
+			error("Attempt to override non-existent element - '" .. key .. "'", 2)
+		end
+		for k, v in pairs(redef) do
+			rawset(def, k, v)
+		end
+		local temporary_list = table.copy(list)
+		clear_fn()
+		for k,v in pairs(temporary_list) do
+			if key ~= k then
+				reg_fn(v)
+			else
+				reg_fn(def)
+			end
+		end
+	end
 	local unregister = function (key)
 		if type(key) ~= "string" then
 			error("key is not a string", 2)
@@ -480,7 +506,17 @@ local function make_wrap_deregistration(reg_fn, clear_fn, list)
 			end
 		end
 	end
-	return unregister
+	return override, unregister
+end
+local function make_wrap_reregistration(reg_fn, clear_fn, list)
+	local reregistration = function ()
+		local temporary_list = table.copy(list)
+		clear_fn()
+		for _,v in pairs(temporary_list) do
+			reg_fn(v)
+		end
+	end
+	return reregistration
 end
 
 core.registered_on_player_hpchanges = { modifiers = { }, loggers = { } }
@@ -521,9 +557,19 @@ core.registered_biomes      = make_registration_wrap("register_biome",      "cle
 core.registered_ores        = make_registration_wrap("register_ore",        "clear_registered_ores")
 core.registered_decorations = make_registration_wrap("register_decoration", "clear_registered_decorations")
 
-core.unregister_biome = make_wrap_deregistration(core.register_biome,
+core.override_biome, core.unregister_biome = make_wrap_override_deregistration(core.register_biome,
 		core.clear_registered_biomes, core.registered_biomes)
 
+core.override_ore, core.unregister_ore = make_wrap_override_deregistration(core.register_ore,
+		core.clear_registered_ores, core.registered_ores)
+core.reregister_ores = make_wrap_reregistration(core.register_ore,
+		core.clear_registered_ores, core.registered_ores)
+
+core.override_decoration, core.unregister_decoration = make_wrap_override_deregistration(core.register_decoration,
+		core.clear_registered_decorations, core.registered_decorations)
+core.reregister_decorations = make_wrap_reregistration(core.register_decoration,
+		core.clear_registered_decorations, core.registered_decorations)
+
 local make_registration = builtin_shared.make_registration
 local make_registration_reverse = builtin_shared.make_registration_reverse
 
diff --git a/doc/lua_api.md b/doc/lua_api.md
index 7461127c2..9491d0f0f 100644
--- a/doc/lua_api.md
+++ b/doc/lua_api.md
@@ -5466,21 +5466,44 @@ Call these functions only at load time!
     * Returns an integer object handle uniquely identifying the registered
       ore on success.
     * The order of ore registrations determines the order of ore generation.
+* `minetest.override_ore(name, ore definition)`
+    * Override existing ore.
+* `minetest.unregister_ore(name)`
+    * Unregisters the decoration from the engine, and deletes the entry with key
+      `name` from `minetest.registered_decorations`.
+* `minetest.reregister_ores()`
+    * Clears all ores currently registered and register them again.
+    * Can be used after overriding/unregistering biome/bimes.
 * `minetest.register_biome(biome definition)`
     * Returns an integer object handle uniquely identifying the registered
       biome on success. To get the biome ID, use `minetest.get_biome_id`.
+* `minetest.override_biome(name, redefinition)`
+    * Override existing biome.
+    * Warning: This alters the biome to biome ID correspondences, so any
+      decorations or ores using the 'biomes' field must afterwards be cleared
+      and re-registered. Functions `minetest.reregister_decorations` and 
+      `minetest.reregister_ores` can be used for it.
 * `minetest.unregister_biome(name)`
     * Unregisters the biome from the engine, and deletes the entry with key
       `name` from `minetest.registered_biomes`.
     * Warning: This alters the biome to biome ID correspondences, so any
       decorations or ores using the 'biomes' field must afterwards be cleared
-      and re-registered.
+      and re-registered. Functions `minetest.reregister_decorations` and 
+      `minetest.reregister_ores` can be used for it.
 * `minetest.register_decoration(decoration definition)`
     * Returns an integer object handle uniquely identifying the registered
       decoration on success. To get the decoration ID, use
       `minetest.get_decoration_id`.
     * The order of decoration registrations determines the order of decoration
       generation.
+* `minetest.override_decoration(name, decoration definition)`
+    * Override existing decoration.
+* `minetest.unregister_decoration(name)`
+    * Unregisters the decoration from the engine, and deletes the entry with key
+      `name` from `minetest.registered_decorations`.
+* `minetest.reregister_decorations()`
+    * Clears all decorations currently registered and register them again.
+    * Can be used after overriding/unregistering biome/bimes.
 * `minetest.register_schematic(schematic definition)`
     * Returns an integer object handle uniquely identifying the registered
       schematic on success.
@@ -5493,7 +5516,8 @@ Call these functions only at load time!
     * Clears all biomes currently registered.
     * Warning: Clearing and re-registering biomes alters the biome to biome ID
       correspondences, so any decorations or ores using the 'biomes' field must
-      afterwards be cleared and re-registered.
+      afterwards be cleared and re-registered. Functions `minetest.reregister_decorations` and 
+      `minetest.reregister_ores` can be used for it.
 * `minetest.clear_registered_decorations()`
     * Clears all decorations currently registered.
 * `minetest.clear_registered_ores()`
@@ -9566,6 +9590,10 @@ See [Ores] section above for essential information.
 
 ```lua
 {
+    name = "default:iron_ore_1",
+    -- Optional field name. This is used as key in minetest.registered_ores table.
+    -- Nameed ores can be overriden by minetest.override_ore function.
+
     ore_type = "",
     -- Supported: "scatter", "sheet", "puff", "blob", "vein", "stratum"
 
@@ -9765,6 +9793,10 @@ See [Decoration types]. Used by `minetest.register_decoration`.
 
 ```lua
 {
+    name = "default:grass_decoration",
+    -- Optional field name. Is used as key in minetest.registered_decorations table.
+    -- Named decorations can be overriden by minetest.override_decoration function.
+
     deco_type = "simple",
     -- Type. "simple" or "schematic" supported
 
@@ -9928,7 +9960,7 @@ Chat command definition
 Used by `minetest.register_chatcommand`.
 
 Specifies the function to be called and the privileges required when a player
-issues the command.  A help message that is the concatenation of the params and
+issues the command.  A help message tdecorations the concatenation of the params and
 description fields is shown when the "/help" chatcommand is issued.
 
 ```lua
diff --git a/games/devtest/mods/basenodes/init.lua b/games/devtest/mods/basenodes/init.lua
index 249c7fbd8..2953402cb 100644
--- a/games/devtest/mods/basenodes/init.lua
+++ b/games/devtest/mods/basenodes/init.lua
@@ -20,6 +20,12 @@ minetest.register_node("basenodes:desert_stone", {
 	groups = {cracky=3},
 })
 
+minetest.register_node("basenodes:test_ore", {
+	description = "Test ore in stone",
+	tiles = {"default_stone.png^basenodes_test_ore.png"},
+	groups = {cracky=3},
+})
+
 minetest.register_node("basenodes:dirt_with_grass", {
 	description = "Dirt with Grass",
 	tiles ={"default_grass.png",
diff --git a/games/devtest/mods/basenodes/textures/basenodes_test_ore.png b/games/devtest/mods/basenodes/textures/basenodes_test_ore.png
new file mode 100644
index 000000000..1de3a9ada
Binary files /dev/null and b/games/devtest/mods/basenodes/textures/basenodes_test_ore.png differ
diff --git a/games/devtest/mods/mapgen/init.lua b/games/devtest/mods/mapgen/init.lua
index a5f9128fb..bb122a90f 100644
--- a/games/devtest/mods/mapgen/init.lua
+++ b/games/devtest/mods/mapgen/init.lua
@@ -53,8 +53,10 @@ end
 
 minetest.clear_registered_biomes()
 minetest.clear_registered_decorations()
+minetest.clear_registered_ores()
 
 if minetest.settings:get_bool("devtest_register_biomes", true) then
+	minetest.log("action", "Devtest: register biomes")
 	minetest.register_biome({
 		name = "mapgen:grassland",
 		node_top = "basenodes:dirt_with_grass",
@@ -101,4 +103,85 @@ if minetest.settings:get_bool("devtest_register_biomes", true) then
 		heat_point = 50,
 		humidity_point = 50,
 	})
+
+	minetest.register_biome({
+		name = "mapgen:desert",
+		node_top = "basenodes:desert_stone", -- error, to try override of it, to fix it
+		depth_top = 1,
+		node_filler = "basenodes:desert_sand",
+		depth_filler = 1,
+		node_riverbed = "basenodes:sand",
+		depth_riverbed = 2,
+		node_dungeon = "basenodes:cobble",
+		node_dungeon_alt = "basenodes:mossycobble",
+		node_dungeon_stair = "stairs:stair_cobble",
+		y_max = 31000,
+		y_min = 4,
+		heat_point = 60,
+		humidity_point = 40,
+	})
+end
+
+if minetest.settings:get_bool("devtest_override_biomes", true) then
+	minetest.log("action", "Devtest: override biomes")
+	minetest.override_biome("mapgen:desert", {
+		node_top = "basenodes:desert_sand"
+	})
+end
+
+if minetest.settings:get_bool("devtest_register_decorations", true) then
+	minetest.log("action", "Devtest: register decorations")
+	minetest.register_decoration({
+		name         = "mapgen:junglegrass",
+		deco_type    = "simple",
+		place_on     = "basenodes:dirt_with_grass",
+		sidelen      = 16,
+		noise_params = {
+			offset  = 0,
+			scale   = 0.007,
+			spread  = {x = 100, y = 100, z = 100},
+			seed    = 329,
+			octaves = 3,
+			persist = 0.6
+		},
+		y_max       = 30,
+		y_min       = 1,
+		biomes      = {"mapgen:grassland"},
+		decoration  = "basenodes:leaves",
+	})
+end
+
+if minetest.settings:get_bool("devtest_override_decorations", true) then
+	minetest.log("action", "Devtest: override decorations")
+	minetest.override_decoration("mapgen:junglegrass", {
+		decoration = "basenodes:junglegrass"
+	})
+
+	minetest.reregister_decorations()
+end
+
+if minetest.settings:get_bool("devtest_register_ores", true) then
+	minetest.log("action", "Devtest: register ores")
+	minetest.register_ore({
+		name           = "mapgen:test_ore",
+		ore_type       = "scatter",
+		ore            = "basenodes:desert_stone",
+		wherein        = "basenodes:stone",
+		clust_scarcity = 8 * 8 * 8,
+		clust_num_ores = 9,
+		clust_size     = 3,
+		y_max          = 31000,
+		y_min          = -31000,
+		biomes         = {"mapgen:grassland_under"}
+	})
+end
+
+if minetest.settings:get_bool("devtest_override_ores", true) then
+	minetest.log("action", "Devtest: override ores")
+	minetest.override_ore("mapgen:test_ore", {
+		ore    = "basenodes:test_ore",
+		biomes = {"mapgen:grassland_under", "mapgen:grassland"},
+	})
+
+	minetest.reregister_ores()
 end
diff --git a/games/devtest/settingtypes.txt b/games/devtest/settingtypes.txt
index c4365643e..ffa627fb7 100644
--- a/games/devtest/settingtypes.txt
+++ b/games/devtest/settingtypes.txt
@@ -30,3 +30,18 @@ devtest_dungeon_mossycobble (Generate mossy cobblestone) bool false
 
 # If enabled, some very basic biomes will be registered.
 devtest_register_biomes (Register biomes) bool true
+
+# If enabled, minetest.override_biome function will be tested over some of registered biome/biomes.
+devtest_overide_biomes (Override biomes) bool true
+
+# If enabled, some very basic decorations will be registered.
+devtest_register_decorations (Register decorations) bool true
+
+# If enabled, minetest.override_decoration function will be tested over some of registered decoration/decorations.
+devtest_overide_decorations (Override biomes) bool true
+
+# If enabled, some very basic ores will be registered.
+devtest_register_ores (Register ores) bool true
+
+# If enabled, minetest.override_ore function will be tested over some of registered ore/ores.
+devtest_overide_ores (Override ores) bool true