oops, I'm sorry dkays, I just realized I read your initial post wrong. Kittens born in Sept, remvoed T-Giving. So they were about 8 weeks old. Few weeks go by and behavior starts. So it may not be related to the litter at all. She most likely had them weaned by that time and 8 weeks is ample age to rehome the babies. I believe this is a physical problem. She is choosing the best place to alert you to it, which is her chosen humans (your DD) bed. Get her to the vet ASAP. In the mean time do as others have suggested and cover the bed with a tarp or shower curtain liner or do not allow her access to your daughters room. There is something wrong and she is letting you know the only way she knows how.