She might be nervous about going inside the dog house, only one way out and easily trapped. (guessing dog house isn't currently used but might still smell like dog) Maybe a dish of food for her to make it seem safer? Or could you put the kittens in a box on the porch or something more "open" but...
:love Finn!!! :love
He's getting to be a handsome guy, sorry his foot never fully straighten out. Looks like he's becoming a full time babysitter for you... 😁