Model Swapping: Lillie over Marnie

Question

Recently I've been seeing a decent amount of model swaps and edits for these games, the extent of which seems pretty impressive. I'm just a simple man with some half-decent Photoshop skills, so I wouldn't know where to begin with that sort of thing. That being said, something I would love to see is Lillie from Sun and Moon replacing Marnie, as the two are both favorites of mine. I've worked on this in some ways, such as replacing references to Marnie's name in dialogue with Lillie's, but of course, that only gets me so far.Now I know a few basics, such as how to locate models and make aesthetic changes to them, but that's about it. If anyone wanted to take on the challenge, I'd love to hear it!