Su 35 is different plane with much more powerful engines and new avionics, which later used in Su 57.It's certified on Su-35 which is a derivative of su30mki. So there should be no problem in integrating it on su30mki too. Also by all means these 12 will be coming with S117 engines too with 144kn Power. Or may I say a template of super Sukhoi...
And integration to MKI is even more complicated as @random radio once said due to it being highly customised using western, Israeli and Indian subsystems as we all know.