Weddingbee boards

So far, our wedding party is 3 bridesmaids, 2 bridesmen, and 3 groomsmen (with two yet to be determined).

My girls are wearing 3 different blue knee length dresses in different shades.  The groomsmen, who are all the BMs husbands, will be wearing white shirts with blue ties to match their dresses and black or gray suits (I'm pushing for gray, but FI isn't quite sure yet).  FI is wearing a blue shirt with a white tie, and he wants to wear a vest rather than a jacket.

I want my bridesmen to be distinctive from the groomsmen.  I would have liked them with blue shirts and white ties, but I don't want them to be the same as FI.  Can I put them in blue shirts with black ties and black suits if the groomsmen are wearing gray?  If the  groomsmen are wearing black, can I put them in gray?  Do pocketsquares work (they'll both wear them if I ask)?  Different bouts?

I don't know what to do.