Some siblings stay together, some take off as soon as they are competent hunters. Lucy and Ivy ended up together in West Winnipeg but they may or may not have travelled together - just as likely that they both came back to the same place at about the same time. This year Trey and Princess appeared at the same time but chances are that was the first time they had seen each other since they left in the Fall. Last year there was close to two weeks between their returns. Madame, Trey's Mom, used to overwinter in the City while his dad, T-Rex, used to head out each fall. In 2007, Mistral and Chinook hung out together for quite a while after fledging but Hurricane disappeared almost as soon as he could work out how to kill things.
Short answer is young may hang out together while in their natal area, but after that we really don't know, the evidence seems to indicate that they don't. Some may hook up again later if they return to their natal area later. But that's not hard-and-fast, I'm sure there have been documented exceptions (there are always exceptions with these birds) but I don't know of any off hand. As for mated pairs, I know ours always seem to disappear individually, and usually with a significant amount of time between departures. Again I don't know of any reports of mated pairs hanging out with one another after they have left on migration. Pairs that decide to overwinter, do hang out with one another (check out the Ohio webcam site for a nice example).
Answer your question somewhat Cammie?
