Margaret Seiler
From This Might Be A Wiki
Margaret Seiler was an early girlfriend of John Flansburgh. She introduced him to Glenn Morrow of Bar/None Records, who would go on to sign TMBG to the label. According to Myke Weiskopf's Early Years Handbook, Seiler got Morrow interested in the band by giving him a copy of the 1985 Demo Tape.
In a 2018 podcast interview, Morrow recalled:
I was in Tompkins Square Park, and I ran into a woman I knew from high school, and she was John Flansburgh's girlfriend. And she introduced me. At that point they had flexi-discs that they were hammering to telephone poles as a way to promote themselves.
Seiler sang "Boat Of Car," and was asked to sing what would wind up being Laura Cantrell's parts on "The Guitar," but wasn't available.