C.C.
You need to what you feel is best. Could she be hurt if you ask someone else yes but she did tell you that she would understand if you chose someone else. If it is important to you to have the same godmother for both of your sons than I would let her mother stand in for her. Is there a reason she cannot make the baptism this time? Personally I think it is important for the actual godparents to be there that is the first step in saying I will be there for you always but I also understand that sometimes because of locations and where people live it is not easy. I am having my children baptized on the 27th of this month and as it took a rescheduling I was able to get both godmothers and my uncle who is godfather to both of my children soon. You already rescheduled it twice on her account and I am sure you informed her along the way of dates and changes. If your gut is telling you to pick someone else than do it. Sit down and talk to her about it. How would she feel and tell her to tell you the truth. If she doesn't want the responsibility than she should just tell you so or if she does but cannot absolutely be there for whatever reason she would like to have her mother stand in for her. Whatever decision you make it will be the right one. God bless you and your family.