Register them as Unaccompanied Minors and then check in and travel separately (although on the same aircraft), in a disguise in case they spot you.
(Fairly obviously, do not tell them that you are travelling.)
If there's a minimum age for UMs you may be ably to lose only one of them in this way, but that's a big gain. The one-year old will be easier to manage, and don't forget the Calpol.