I think that would be an awesome sibset!
Ursula would have to be older though; it just sounds so much older than Crispin IMO...
I don't think Ursula Catherine is too long, but it is a little mismatched. No other family names?
Otherwise, I'd like Ursula Rhiannon, Ursula Rain, Ursula Olive, Ursula Onyx, Ursula Gwen, Ursula Kaia, Ursula Kate (?)