Is there not a proscription against being friends with an akum? Is a ger’s blood relatives excluded from that?
Considering that Rav Leff says that a ger is permitted to engage in yichud and touch his/her close relatives, it is also understood that s/he can remain in social contact with them.
what happens if a parent has a child who converts…therefore he is now considered “parentless”
In a certain halachic sense, yes. Hence the rule that a ger is “as a newborn child.”
then later on, the parents convert…are they now deemed parent and child again?
To the best of my knowledge, no.
The Wolf