Sorry A B C, but if your airline SOP's say no infants on the lap after 2, then that does not give you a years grace. By doing what you are doing, not only are you helping to create the confusion amongst parents and problems for other crew but you are leaving yourself open to all sorts of problems if something goes wrong.
TCU,
I agree that there is probably little difference between a childs spine at 1 yr and 364 days old and at 2 yrs old, but there has to be a cut off point somewhere.
Jsl