Siwsann George did produce at least three recordings in the '80's. But they are all vinyl recordings and I don't think that any of them are re-issued in CD format.

"Gwyl Mabsant" produced in 1983 produced on an independant label "Gwerin" (Rec No: SYW 240) with Siwsann George & Stuart Brown. Both performed under the title of Mabsant.

They produced "Chwar'e Chwyldro" on the same label in 1986. Rec No: SYW 448.

The following year saw the album "Trwy'r Weiar" produced by Sain, Rec No:SAIN 1404M

Also on the Sain label, the album "Cofeb" was produced in 1989. Siwsann & Stuart were joined on this recording by Steve Whitehead and among others Robin Williamson (Ex Incredible String Band!) The Rec No: SAIN 1508M.

You might well be able get the last two from SAIN?

I haven't heard or seen any thing of Siwsann lately. I don't know whether she is still active on the Welsh folk scene?