Agree, I wouldn’t bank on daughters definitely changing their last name and if they do, it might not be till their thirties by which time they may keep St@nislaw as their professional name.
I don’t think all S ending firsts are a problem. It seems to be better flow or easier to say when they’re longer - eg Eloise over Alice or Tess. With non-S ending names, I think both short and long can work.
I would keep Vincent for sure. I think a vintage-y but more regal and international name (which Vincent is) would sound best.
Others you might like:
Conrad - really like this!
Calvin
Hugo
Oscar
Viggo
Fabian
Patrick
Asher / Ashby
William
Reuben
Everett
Benedict / Benjamin
Sylvan
Walter
Winston (similar to Vincent but prob means can’t use Vincent down the track)
(I know DH not on board but, the -ie/y ending is the easiest flow to last name).
Imogen
Rosamund (“Romy”) - one of my fave suggestions
Emilia
Athena
Maribel
Reina
Bianca
Yasmin
Elara
Aurora
Francesca
Helena (“Leni”)
Rosalie