I apologize if this has already been covered. But can you have two watches on one profile in Garmin Connect? I just got the forerunner 15 but I think I want to keep my forerunner 10 sometimes.
You should be able to have several devices without problems simply add it to the connect account in the usual way. I have my Garmin swim and 610 on my account and for a while had a 210 without any problems.