法華義疏 9.219

9.219

亦得也。本是一佛分為多佛，本是一乘開為三乘，今既集分身之佛皆是一佛，亦會三乘以歸一乘也。

They can indeed. Originally one Buddha was divided into many Buddhas, and originally one vehicle was opened into three vehicles. Now, since the emanated Buddhas are assembled, all are one Buddha; this also integrates the three vehicles to return to the ekayāna.