Finally figured this out while trying relentlessly to get my custom mortar and pestle to have my custom resource engrams in the inventory. First off, do not attempt to make a child for the mortar and pestle or inventory BP. They need to be dup’d. In order to actually get the mortar and pestle (or any crafting stations base BP) to reference its inventory BP, when you open the dialog to edit the asset, go to components in the top right corner. In there add a new component (“Add Component” in list on left) and add the primal inventory BP for your crafting station (ex. primalinventoryBP_MortarAndPestle_Child_C). Once this is done, make sure to check the references of the base BP for your crafting station. It should reference the inventory BP now. Your custom resources can be children however, as long as the engrams are remapped in the PrimalGameData_BP(cutsom). Hope this helps and also helps anyone who has this problem in the future.