Thanks Carol, much appreciated. 
Eileen, I'd say uncle Ted looks about 3, give or take some months; on that basis the lady could be either aunt, but it would mean Elizabeth died not long after the picture with Ted was taken--the feasibility of it being her might depend on what she died of.
Looking at the images below, if it's Sarah she would have been about 41, Elizabeth would have been about 36. To be honest I don't think either aunt fully fits the lady in the photo with Ted. If I were to choose one, I'd make it Sarah: despite the different styles, her hair is parted in about the same place in both pics and her nose/mouth/chin relationships are closer than that of Elizabeth who has a fuller face, larger chin and closer-together nose and mouth. There are some similarities to Elizabeth as well but, on balance, if there are no other possibilities for a "favourite aunt" I'd have to go with Sarah.
Peter
Thanks so much Peter, my thought was that it had to be Sarah. About a year before Uncle Ted died he discovered where 8 of the McNamee family were buried and he paid for a headstone and this is what he has on it. Sarah was obviously a favourite aunt. I just couldn’t reconcile the 2 women, although I did think the jaws were the same. I grew up hearing from my Mom how much Sarah disliked her and how bad tempered Sarah was so it was a surprise to realize that Ted had a completely different outlook. Plus I was told that Sarah had flaming red hair but she must have died it at the time of that pic.
It is fun trying to figure out little stories from the past.
Thanks again to everyone, you are all such talented restorers and I appreciate you.
Eileen