I had Julian on my list because I liked the nickname Jules. I like that one.

Re Vincent, I don't see a problem with naming DS5 one of DS1's middle names. Middle names rarely get used in general so only your close family & friends would know. And if you really like, then why not?

I'm with the majority on Alvin though - my first thought reading the title was "and the chipmunks". Being a kids show, & kids being rather tactless, I think I would avoid it personally.

Good luck