I think the girlfriend had talked to Crump before she talked to the police, so anything she says she "remembers" is suspect--Crump may have told her what she needed to say. Her "testimony" was a major part of Corey's rationale for charging Zimmerman with second-degree murder.
If Crump told Dee Dee to say that Trayvon made it to his father's house and went back out to confront Zimmerman, he screwed up big-time.