So, I have a plot in which a half clan litter is produced, but only one survives. It will think Jewelpelt is his mother when it is actually Mistypaw. They can find out by spying on Mistypaw when older and meeting Spider where they talk about it. They will get mad and try to kill Spider later, thinking it was his idea for her to give the kit up. They will fail, and Spider will tell Mistypaw who will confront them. Telling them it was her choice because she was scared after the siblings died.
After that, what happens is up to you!
There is one slot and the form is a free for all. If you want a stillborn that can haunt Mistypaw, you can apply for that as well. There will be three stillborns, so yeah.