Laughing, Give your son plenty of space and time. Your love will provide his a soft spot to land. He's not ready to land just yet, but he will be.
You have to remember that your son hasn't been around Dick for a long period of time and he's trying to win his father's admiration and validation. This is a brand new adventure for your son, i.e., he thinks he has his dad to himself for a while w/o your daughter being around. But, the euphoria, just like any euphoria will wear thin and that brass ring will most definitely begin to tarnish. Time is on your side. Sit patiently and the answers will come.
It's a positive sign if your son is communicating with a few of the kids back in your area. At least he didn't cut all ties and those connections will be what helps him to decide to return. He'll miss all of the fun and activities that they are particpating in.
I know it's got to be difficult for you and your daughter right now, but both of you will support each other and what feels like time creeping along, will not be so once you can adjust to him being away for a bit. Laughing, he will return home. There's a reason that God pull this rabbit out of the hat and maybe it is to expose Dick's behavior to your son, after all of this time. We just don't know, but God will watch over your son and he will guide him along the way. I have a lot of faith in him.
Take care of yourself.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.