I'm starting to feel weird ending up as some sort of tireless defended of DA, but it's just cause such a troubled soul (let's call it that) as opinions about her seem to paint a picture of; is, IMO as likely to be involved in a terrible crime (with whatever reasons, unknown to me), as to end up turned into a scapegoat.
Cause it would look absolutely horrendous in everybody's eyes if she'd kept living alone with TT. People would talk and they would talk a lot even if she had pristine reputation prior to the disappearance.
She may not care about her reputation, especially if innocent (cause logically it'd make much more sense to have two people there, so someone could be always by the phone in case that Rachel will call), but I can see her doing that for the sake of her mother and/or brother, to support them, or ending up convinced that they desperately need her ther... just to realize pretty darn fast that terrible home is still terrible home and she has to get out of there asap.
I'd even say that's a cliche with abuse victims (to get back in the troubling times despite of absolutely hating that place) as well as for the toxic household to keep the ability to suck people back in, using such events as sickness, death, divorce or disappearance as an excuse.
And if it wasn't as toxic as it seems to be, then just being their daughter is good enough excuse.
Having a job doesn't equal being able to pay rent I guess.