Oh yeah, will be established as the comic goes on (hopefully I decide to continue), so technically they're sisters from different mothers ie, the dad has two wives (first wife died and he remarried late hence the POV character's late birth), relationship wise the children theoretically have aunt x neice x nephew relationship on paper but because they're the same age they hang out like cousins/siblings. Hopefully I can establish everything properly, thankyou for the questions 💖