I Was Watching A Isabel Sanford Interview Off Of Google Videos And She Said That She Originally Went In To Read The Part For The Aunt She Taped Her First episode Then A Week Later They Had Her Come Back And Read For The Mom.
so that explain where the aunt cames From.

Aunt of Who

Aunt of Who
Lionel

I wonder who would have played Mrs Jefferson if that was the story

I know Henry's wifes name is Ruby, as stated in the Jefferson's episode "Uncle George and Aunt Louise".