Faye is great- I think it would be taken seriously. There are way more cutesy names being given these days. As for middles, I think something longer (i.e, more than one syllable) I think it goes well with your other childrens names as well.
A few ideas (sorry for any repeats!):
Hope this helps!
Thank you, everyone, for great suggestions.
I really like Faye Olivia, Faye Caroline and Faye Louise.
For some reason, the cadence of two-syllable names with the stress on the second syllable (iambic meter) seems to sound best to me. Examples:
Faye Michelle (not sure I even like Michelle, but I like the way it sounds)
Faye Renee (wouldn't use because of the rhyming, just using it as an example)
Any other suggestions are welcome. Thank you!