It's such a complicated situation. Once you pass the grief period - which in itself is difficult because it isnt a normal grief of losing someone in death. But the fact that you can still possibly run-in or hear from them at any moment. After this than yes I do feel you lose that connection with them. Your relationship is severed and often the brutal treatment and experience turns you off from even wanting to be close to such members.
Let's hope your mum and step dad see the light before you get any phone calls as such :)