I know this question may seem a bit simple, but I would like to know about how fission products of an element are formed. There seems to be no way for krypton-92 and barium-141, the immediate fission products of U235, to decay into a fission product like caesium-137 or technetium-99. Instead, I found they quickly decay to the stable nuclides zirconium-91, zirconium-92, and praseodymium-141, and the intermediate radioactive nuclides all have half-lives of within a few months.
So, my question is, how are these other fission products formed?