I've adored
Eugenia ever since I met a young woman with the name. She went by Genia, but
Genie works just as well. I love the nn
Jeanie, so
Genie is an easy transition. Go for it.
Millie is adorable, but I think it needs a more formal name. I know a
Millie in her 40's. It's short for
Amelia. I can also see it short for:
Melinda,
Emily /
Emilia,
Camilla /
Camille,
Melisande /
Millicent,
Melina,
Melanie,
Mary,
Eumelia (although not with a sister
Eugenia), or
Jamila.
Great names. :-)