Fair or unfair

So apparently my pregnant cat and her brother got themselves in trouble cause my soon to be sister-in-law and i both have hamsters and she is apparently mad cause she thinks one cats have killed her hamster when it could be running around her room after we read that they hide for warmth and dark places. Its been few hours of the same day we are still trying to find her hamster yet actually we are all sitting down watchin tv and had left hamster food for it when it comes back.

So tell me is it fair that my soon to be sister-in-law to get rid of both cats just cause its possible the hamster can still be in its cage under its log or has gone out of its cage by itself. When i was awake and all i hear is a small crash and then my cats playing together and i wont be able to see my cats babies getting born and being put at a shelter when it cant be their fault just cause the same thing happened with my hamster and its still alive?

And my sister-in-law is thinks a new born kitten is gonna attack her new hamster tomorrow and thinks all i want is the kitten just cause its small when i do got reasons i want to have a kitten from my pregnant cat.