Well, I think that
Hallie is a nickname for
Harriet that just isn't used as much. So, clearly
Harriet would work.
However, I will say that I like
Hallie as is. I grew up
Heidi, with a sister
Holly... so have always been drawn to the
Hallie,
Haidee and
Hailee names. I think they work fine for children and adults.
Plus,
Hallie Rose is adorable.
As for alternatives, you listed
Halima, but forgot
Halina. I think that would work swell and
Halina Rose is also quite lovely.