I wouldn't give twins rhyming names.
Maisie is pleasantly retro, but I really don't enjoy hyper-Methodist
Wesley. No doubt she used Koy for a reason, but it sounds like the dictionary word 'coy', which is not an attractive attribute: perhaps it would have been worth thinking about an extra middle name,
Wesley Jason Koy or something. It would change nothing, but it would serve to dilute the impact of Koy.
Joanne is, I'm sure, all right: I prefer
Joan and especially
Joanna, but it does give little
Maisie a nicer mn than her brother. All in all, she scores.