When the twins were taking 2 naps a day their schedule was roughly:
Up for day 6:30-7:00 am
Nap from 10:00 to 11:00 (I usually woke them up - absolutely not later than 11:15)
then they would go down for nap again at 2:00 (Becca too) and they would all sleep until about 4:00 or so. (Again I woke them up alot by 4:15)
Bed at 7:30 - 8:00 for the twins a little later for Becca.
I dropped the twins nap around the same time Becca started preschool, so now all 3 go down for a nap at 1:30 and sleep until about 4:00.
I agree with
pp try to push G's nap back a little so that A will still go to sleep and they will be down at the same time.