Ohh, i love your idea! i think it's a super cute thing to do with your oc's
About the genre, i think that comedy, or slice of life and romance work well together, i reccomend to keep 2 out of these 3 (just a very tiny advice though: i think romance would work the best, not only because it's fitting but also because Romance is the most browsed webcomic genre usually, from what i saw )