His family probably had some kinds of connections without official ties. That was a situation that was not rare.
Yes, it's quite possible. Or they were possibly members of the satellite parties - it's often forgotten about that other political parties did exist in Poland outside of the PZPR. From what I remember, you could hold high up positions in one of the myriad of organisations allied to the PZPR without being a Party member as well.
I'm not a rabid anti-communist, but someone didn't belong to the upper tiers in society then without being compliant in some way.