Zee didn't acquired filmkraft films for getting the new films, as filmkraft nowadays rarely makes any films now.
Zee actually acquired filmkraft movies to strengthen their old bollywood library with films like koyla, karan Arjun, koi mil gaya etc
Now most probably krish and krish 3 will expire from Sony after sometime as a part of filmkraft deal and will go to zee.
Anyways these movies like koyla, karan Arjun, koi mil gaya provides massive trp on zee Anmol cinema as its back to DDFD
So I think krish and krish 3 will also fall in the same category once zee gets it