Even if some elder bodies follow the advice in the elder book not to DF people for associating with DF/DA relatives, they keep this information pretty well hidden. If you ask a r&f JW if they could be DFd for doing it, the vast majority would say yes. Otherwise you would see few family members participating in shunning. And since WT article after WT article tells them they should, the natural conclusion among JWs is that they will be punished if they don't follow those rules. This is an understandable conclusion since they will be DFd for associating with non-family who are DF/DA.
IMO the WT wants it that way. They are at risk for bad publicity if they get a lot of people going public with stories about being kicked out of the org for speaking to their own family. Yet they can get the JWs to act that way anyway because they believe they will be DFd for doing it.
As someone who is being shunned by family members myself, (I'm not DF/DA to my knowledge, but started attending another church years after leaving the WT, which is what led to the shunning) I know they would not do this if they didn't feel they had to. I happen to know that it hurts them to do it.