You're assuming that your age doesn't change as you move artificially through time, but that it does change as you move naturally through time.
Therefore you would age the amount of time that you went forward naturally, while the others would be the same age as they were when you sent them, plus whatever amount of natural time it takes to travel through artificial time.
Example: You and your two friends were all born in the Central Time Zone at 11:00 am on November 15 1990, meaning that you're all exactly 20 years old at 11:00 a.m. on November 14, 2010.
Now, at 11:00 a.m. On November 15, 2010, you send one traveler backwards to 11:00 a.m. November 15, 2000, and the other traveler forwards to 11:00 a.m. November 15, 2020: 10 years in each direction. Assume that each area that you send them to is a safe point where they can "land" without any problems, such as other mass being in that spot (i.e. if a rock or other solid substance occupies the area where they're to land).
You now wait 10 years and, at 10:59 a.m. on November 15 2020, you stand a few feet away from where the forward time traveler stood (so that he doesn't materialize in your area, which would cause a conflict). At exactly 11:00 a.m., the forward time-traveler will materialize on the spot he was on, since that's the place and point of time that he was sent. You're now 30 years old, but the forward traveler is still 20 years old (plus possibly a few seconds for traveling through time).
Now the two of you go back in time to 10:59 a.m. November 15 2000 and stand on spots near, but not exactly on, the spot that you sent the backwards-moving traveler to. At exactly 11:00 a.m. she will materialize on that spot, since that's the place and time to which she was sent. She will also be 20 years old, plus a possible few seconds for traveling through time. Your forward-moving friend will be 20 years and a minute or so old, and you will be 30 years and a couple of minutes old.
As the second poster said, too much time on our hands.....