Fixes it all, I hate it (#23008)

code/game/objects/items/stacks/medical_packs.dm

@@ -129,6 +129,7 @@
 	icon = 'icons/obj/stacks/miscellaneous.dmi'
 	icon_state = "gauze"
 	origin_tech = "biotech=2"
+	merge_type = /obj/item/stack/medical/bruise_pack
 	max_amount = 12
 	heal_brute = 10
 	stop_bleeding = 1800
@@ -173,6 +174,7 @@
 	name = "improvised gauze"
 	singular_name = "improvised gauze"
 	desc = "A roll of cloth roughly cut from something that can stop bleeding, but does not heal wounds."
+	merge_type = /obj/item/stack/medical/bruise_pack/improvised
 	heal_brute = 0
 	stop_bleeding = 900
 
@@ -183,6 +185,7 @@
 	desc = "An advanced trauma kit for severe injuries."
 	icon_state = "traumakit"
 	belt_icon = "traumakit"
+	merge_type = /obj/item/stack/medical/bruise_pack/advanced
 	max_amount = 6
 	heal_brute = 25
 	stop_bleeding = 0

code/game/objects/items/stacks/sheets/mineral.dm

@@ -441,6 +441,7 @@ GLOBAL_LIST_INIT(plastitanium_recipes, list(
 	throw_speed = 1
 	origin_tech = "materials=6;abductor=1"
 	sheettype = "abductor"
+	merge_type = /obj/item/stack/sheet/mineral/abductor
 	table_type = /obj/structure/table/abductor
 
 /obj/item/stack/sheet/mineral/abductor/fifty

code/game/objects/items/stacks/stack.dm

@@ -24,7 +24,8 @@
 	var/amount = 1
 	var/to_transfer = 0
 	var/max_amount = 50 //also see stack recipes initialisation, param "max_res_amount" must be equal to this max_amount
-	var/merge_type = null // This path and its children should merge with this stack, defaults to src.type
+	/// This path and its children should merge with this stack, defaults to src.type
+	var/merge_type = null
 	var/recipe_width = 400 //Width of the recipe popup
 	var/recipe_height = 400 //Height of the recipe popup
 	/// What sort of table is made when applying this stack to a frame?