Sobeknefru was the daughter of Amenemhet III who reigned over Upper and Lower Egypt for 46 yrs. It was Amenemhet III and his father Senusret III who were co-reigning at the time when Moses was born to the Hebrew slave Jochebed. A decree was given by the pharaoh that the midwives kill all male babies born to the Hebrew slaves. Moses was found hidden among the reeds of the Nile by the Princess (Sobeknefru) when she went down to the Nile to bathe.
Sobeknefru had no children and so there were no male heirs to the throne to continue on from Amenemhet III. Sobeknefru ended up adopting Moses, raising him as her own and grooming him to be the next pharaoh Amenemhet IV.
Amenemhet IV did in fact co-reign with Amenemhet III for 9 years, however, Amenemhet IV seems to have disappeared from the record because when Amenemhet III died, his daughter Sobekneferu had to take the throne. Sobeknefru reigned for 8 yrs and then she died. When she died, the 12th dynasty came to an end.