"Erica" was used from the beginning as a middle name on her name change court decision, passport application etc. but, interestingly enough, not used on her SSN application.
The court decision had been the week before (5 July 1988) she filed her SSN application (12 July 1988), & the next day when she obtained her Texas ID card (13 July 1988) she supplied her middle name. Maybe she'd only decided on Lori Erica Kennedy a few weeks before (or less) she applied for a SSN & she had forgotten which middle name she picked when she filled out the application.
Speculating further...
One thing that we have all assumed is that LEK moved to the Dallas area in July 1988; what if she had moved there before that month? What made me wonder is the username "Spring/Summer 1988" picked, which makes better sense if S/S1988 had first met her in March or April, not July 1988.
If that is correct, that leads to another question (as is always the case here): why did LEK say she moved to the Dallas area July 1988? Building on S/S1988's reminiscences, maybe that was the month LEK's mother -- the woman S/S1988 says LEK was living with -- died. If so, knowing that her mother was likely to die soon, & having no other links to her past life, it was during those last months that she took the steps to assume her new identity -- which included selecting a new name.
If we could compile a list of all women who died in Irving, Texas July 1988 we might find a link to LEK's birth name. And solve the mystery.
Then again, this is just as likely to be another wild speculation about this case. And maybe even more incorrect than any other theory about her. I can't help wondering that if there was anything to S/S1988's story, & if he did tell agent Velling about knowing her, that agent Velling would have solved & closed the case before retiring.