As I've said, in-law will be too much.
In fact, let's change POD to "shishecka" (the Peter Petrovich born in 1715) being healthy and with non-retarded development.
If his dad dies on schedule (surviving son can butterfly his exact death date a bit later, different partying and carpenter schedule), young *Peter II will be pronounced Tsar with nominal regency of his mother.
However, if we push Peter the Great's death date to 1730, we avoid a bit of regency inconvenience, but young Emperor will be in the same position as his grandfather Alexis Mikhailovich - dominated by his tutor. And I think that Menshikov will prop up Catherine as proxy regent.