Growing up anxiety

Garrett has been increasingly concerned about growing up and moving away. He used to tease me about it, knowing that the thought of either of my kids leaving breaks my heart. Recently, though, he's become worried that we're going to kick him out and change the locks or something. I've tried calming his fears by telling him that he can live here as long as he likes (just a little fib), but he still asks that if he chooses to leave, I give him directions so that he can find his way back for a visit. Then he became focused on Scout moving out and having her own family. A few days ago Garrett asked, "Mommy, when Scout moves out and is a mommy, will you tell me her phone number so I can call her?" Sweet big brother!