if darkage is also installed,

don't register large homedecor lattice lamp or the recipes to
create it or to split it into 8 small lamps. instead, add an
alias to darkage:lamp and a recipe to split that.

homedecor/crafts.lua

@@ -1207,21 +1207,30 @@ minetest.register_craft({
 
 -- wood-lattice lamps
 
-minetest.register_craft( {
-        output = "homedecor:lattice_lantern_large 2",
-        recipe = {
-			{ "dye:black", "dye:yellow", "dye:black" },
-			{ "group:stick", "building_blocks:woodglass", "group:stick" },
-			{ "group:stick", "homedecor:power_crystal", "group:stick" }
-        },
-})
+if minetest.get_modpath("darkage") then
+	minetest.register_craft( {
+		output = "homedecor:lattice_lantern_small 8",
+		recipe = {
+			{ "darkage:lamp" },
+		},
+	})
+else
+	minetest.register_craft( {
+			output = "homedecor:lattice_lantern_large 2",
+			recipe = {
+				{ "dye:black", "dye:yellow", "dye:black" },
+				{ "group:stick", "building_blocks:woodglass", "group:stick" },
+				{ "group:stick", "homedecor:power_crystal", "group:stick" }
+			},
+	})
 
-minetest.register_craft( {
-        output = "homedecor:lattice_lantern_small 8",
-        recipe = {
+	minetest.register_craft( {
+		output = "homedecor:lattice_lantern_small 8",
+		recipe = {
 			{ "homedecor:lattice_lantern_large" },
-        },
-})
+		},
+	})
+end
 
 -- glowlights
 

homedecor/depends.txt

@@ -14,3 +14,4 @@ flowers?
 3d_armor?
 skinsdb?
 mesecons?
+darkage?

homedecor/lighting.lua

@@ -360,13 +360,17 @@ homedecor.register("ceiling_lantern", {
 	walkable = false
 })
 
-homedecor.register("lattice_lantern_large", {
-	description = S("Lattice lantern (large)"),
-	tiles = { 'homedecor_lattice_lantern_large.png' },
-	groups = { snappy = 3 },
-	light_source = default.LIGHT_MAX,
-	sounds = default.node_sound_glass_defaults(),
-})
+if minetest.get_modpath("darkage") then
+	minetest.register_alias("homedecor:lattice_lantern_large", "darkage:lamp")
+else
+	homedecor.register("lattice_lantern_large", {
+		description = S("Lattice lantern (large)"),
+		tiles = { 'homedecor_lattice_lantern_large.png' },
+		groups = { snappy = 3 },
+		light_source = default.LIGHT_MAX,
+		sounds = default.node_sound_glass_defaults(),
+	})
+end
 
 homedecor.register("lattice_lantern_small", {
 	description = S("Lattice lantern (small)"),