1)
Carter,
Morgan &
Brooks work as siblings. If you dont like
Brooks maybe something like
Shelton,
Bradley or Bennet would work.
2)
Ruth and
Delia sound ok as siblings, I just think
Ruth sounds a bit plain with
Delia but it isnt a bad thing.
3) As a family I think I could see them as siblings, it kind of reminds me of a Southern aristocratic family.