Unless Delta is running a transfer bonus promo which they haven't done with meaningful value in several years transfering miles in large quantities is almost always a horrible value. Essentially they charge you the value of the miles 1cpm to move them between accounts which is a terrible deal.
Very few programs allow "free" xfer between accounts (BA Avios is an exception that comes to mind).
Why not just book the tickets for your kids and have them do the same down the road for you as previously suggested?