I think IG's concern is that her ex-therapist will alter them before sending her a copy. I don't think there's anyway to protect against that, unless a computer expert can show that changes had been made, assuming it was all filed electronically to begin with.

In my experience, a therapist will go to any lengths to protect her/himself (emotionally and professionally), regardless of what it does to the client. They can (and will) do what it takes to justify what they've done.