I have no idea of US family, succession, nor immigration law, but my guess would be if she finds out she is in fact a product of his loins, she will want soem form of compensation for geneitically polluting her bloodlines.
Maybe she would be recognised as her daughter, and a bona-fide claim on his estate as well as citizenship to the USA, without ICE. That would mean a) some dilution of hs corruptly acquired gains since office at least, and someone who could stare down ICE and tell them to eff off as she is the offsping of the president - just before they shoot her.
Not only that, but aghast be those evangelical types at their lord and saviour violating yet another sacrosanct rule of theirs. But, hey, he sells them glittery bibles, so all will be forgiven.
This post is as crazy as the world has become.