This is cool (not actually spoilery, just big pictures
)
I'd be convinced Lillian was Jennifer's mother (especially since we know her mother was mentally ill too) if the years matched up but she'd be in her 70s around the time Jennifer is born going off Madeleine Stowe's real age. Then again, this is a show that has time travel and particular people with decelerated aging so it's not entirely outside the realm of possibility
Although I think it's more likely they were just drawing parallels between them due to their similarities.