Another key point is to try and have their afternoon nap at the same time as the 2.5yo. It is possible, I have a 10mo daughter and a 14mo dcb who take their morning naps together and then all the kids (3x 2.5yr olds) go down for an afternoon nap. This way you still get YOUR break!

I schedule the little ones' morning nap between 8:30-9am and I wake them by 10am to make sure they go down for pm nap around 12:30-1pm.