Well actually you have a number of options. Sorry I was a bit pressed for time this morning and I didn't mention all of them. You can chose to have him stay at the keep until the next round of Quests. You can have him retconned into the G1 or you can have him sent to them afterwards (we can work out him giving additional information or orders from the Grey Wardens if you want). Also alternatives include whatever you can think of, I'm open to other ideas!