Actually, I thought about that - after all, 'the Prince' turns out to be related to both Paris and Mercutio, and Mercutio seems to be on good enough terms with the Capulets to warrant an invitation to their big bash (or am I making that up?), even though, when push comes to swashing blow, he allies himself with the Montagues. However, I don't think there is any (other?) hint that Benvolio is related to the Capulets.