I totally understand why you are having a dilema on this, but trust me, dogs adjust very well, mine when they were alive moved from florida to oregon, back to florida in a two year time frame, as long as they are with the humans that love them and care for them and keep them safe they can adjust to anything. But you have to be patient and work with them and teach them its fun and its ok to be inside. I vote for them going with you, I know your Grandpa will miss them, but if he really wants a pet, he can get a dog of his own right??