Theoretical questions regarding sperm donation

Rav,

Theoretical question:

If a Jew had to donate sperm to a sperm bank in Israel anonymously
(where the majority are Jews) and he has no way of knowing who the
potential mother could be. What would the din be for the donors
children, are they allowed to marry any jew? Would we follow the din
of Rov and say that 99.9% of people would not be their brother/sister
and therefore can marry anyone, or they are forbidden to marry anyone
because there is always a safek they could marry their brother/sister?

I am wondering if the poskim have discussed this case and would be
interested in what they had to say.

Regards,

R