Hi there!
Aww, so glad you are liking them!
They sound spoiled already, hehe. Sometimes they have a mind of their own and enjoy certain spots, but if you haven't already, you can move them to a certain spot like a bed & set their Home point so they will sleep there. The Home point also is the center point of their wander range. If their home point is set inside the cottage they should wander around inside, though if the range reaches outside the cottage they could be able to wander outside, but should jump back to their home point inside the cottage when they fall asleep.
I hope this information helps, if you have any other questions or would like some in world help just reach out to me & I will be more than happy to stop by and take a look at your set up to give some pointers on how to keep them where you would like them to be
-FoxieCat