as long as the option to come in is open (and it sounds like it is) I would not force the issue, myself personally. Willow hides under the comforter in the cat room about 20 hours a day, but I don't force him to come down and watch TV with us. Fern (who is way beyond this point now) used to practically live on our 3rd floor. I never forced her to do ANYTHING she did not feel comfortable doing. She came around on her own. First down to the 2nd floor and now she spends almost all her time on the 1st floor where all the activity is. I think if your guys want to come in, they will.