I like
Larisa just fine. It's pretty and uncommon. I also like this original spelling, however, I pronounce it lah-REE-sa because I assume that a person who uses the original spelling would likely use the original pronunciation. If you're planning on lah-RISS-a, then spelling it
Larissa might be less problematic. While I like
Angela, I don't care for the way the vowels run together in the combo,
LarisA Angela. WDYT of
Larisa Catherine or
Larisa Margaret? I also think
Anastasia and
Natalia would sound great as sibs to
Larisa. WDYT of
Anastasia Caroline,
Anastasia Katherine,
Natalia Christina,
Natalia Charlotte, or
Natalia Patricia?
One final thing, since you have so many people to honor, be sure to use the names you love as fns and then work out the mns. You may even have to include two mns to fit them in! ;-)