I did a quick search on Discogs and Allmusic.com and could not find a Colleen Stewart/Therese Heston album. I wonder if it ever was released.

I wish I could have answered your question, NMB. I'm curious too. Your tip about the Lauren Wood photo is the most recent item I've seen about her, so thank you for that. My guess is that she did leave the music business at least by the 90s.