In case it's not obvious: once you find a hamster, it's yours to keep.My initial pick was nene...then the rest and aki last...the guilt trip made me not quickload again after her...at the cost of 2 hamsters...
So, if you go through all nine options and pick up the hamsters during those run-throughs, you'll have those hamsters in your count and images. If you didnt get them, and still have a save from before the choice, you can go back and do it now. Even if you don't use this run-through to create a new on-going save, you'll get to keep the hamsters. It doesn't matter which of the girls is in your actual save going forward, as far as the hamster list is concerned.