Do you just choose names based on sound, or also on meaning? Do you have any idea what your children’s last name would likely be?
I find it hard to advise because I choose names so differently 
Largely based on meanings or family names, and flow of syllables and sounds in the name as a whole.
But here are my random first thoughts for some of your names:
[name_f]Frances[/name_f] [name_f]Louise[/name_f]
[name_f]Dorothy[/name_f] [name_f]Joelle[/name_f]
[name_f]Sally[/name_f] [name_f]Elizabeth[/name_f] (I can’t seem to put a short name with [name_f]Sally[/name_f] without it sounding Southern!)
[name_f]Shirley[/name_f] Vivienne/Abigail/Violet/Margaret
I think I’m going for 2+ syllables to stop it sounding like [name_f]Sally[/name_f] [name_f]Jane[/name_f], [name_f]Lucy[/name_f] [name_f]May[/name_f] etc… but having it end with a consonant sound rather than a vowel sound kind of helps the middle name still feel closed off and shorter? [name_m]Like[/name_m] [name_f]Elizabeth[/name_f] and [name_f]Arabella[/name_f] are both 4 syllables, but the consonant sound at the end of [name_f]Elizabeth[/name_f] somehow keeps it feeling crisper? And while [name_f]Louise[/name_f], [name_f]Joelle[/name_f] etc end in a vowel, the final sound is the consonant, the z or l sound. But don’t know whether that helps at all or is the kind of feel you’re going for!