Welcome back Carole, and nice to meet you. Your boys are adorable!
From what I have read and heard you can retrain them to potty pads from outdoors (or vice-versa) it will just take time, patience and a lot of positive reinforcement! Treats, verbal praise or both should work as long as you keep them on a schedule. That is one more thing I love about this breed,
they are so very smart! I can only speak of what I was told by a trainer and read though,
I am sure someone here will have some personal experience and success with this to share!