It is probably a thing best fixed in ROTJ.
Changing one two words "Obi-Wan" to "Your mother" sorts the problem out with much better efficiency than trying to distort the already problematic PT dialogue.
It was a bit of a mis-step to ignore the one reference to Luke and Leia's mother in ROTJ in the PT but it was also a bit of mistake not addressing this then mysterious character more in ROTJ.
Watching the entire saga now she goes from being the major character she is in TPM to an afterthought in ROTJ and altering that line seals a continuity problem and reminds us of an important character (whether you like the PT or not).
Even if you want to ignore the PT Luke, Leia and Vader all circle this woman and to largely dodge her leaves a hole in the final film.