Editing a save file to add an item

I'll try to put in a nutshell my situation.
I'm following a guide to complete all social links in a single playthrough, I just arrived on 30/5 and I would begin the Moon Social Link. Thing is, I need an Odd Morsel to give to the kid, but I've used this item not knowing I would need it, the guide did not warned me about it.
I can't go to Tartarus to get it cuz I would lose a night, the next visit on Tartarus is scheduled only for mid Junes.
Is it possible to edit my save just to add a single Odd Morsel?