There is always a possibility of that, IMO, but the Barkers were questioned and claimed not to know her. The info about them taking in wayward teens is not quite accurate--though they might have. All we have is what was printed in the mother's obituary:
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=115774245
The relevant quote from the obituary says
From that I think people have extrapolated that they took in wayward teens or homeless people for a night or two and one of those people could have been FLEK. But the wording is so vague and it doesn't really say their 2 night visitors were troubled people at all. If we have more to go on than the obituary, I hope someone will correct me.