I'm sorry for the loss of your piggy.
However I must say, they cannot have any formula substitues!
GP's are herbivores and any milk products and formulas are not good for them. They should be able to eat solids within the first couple days, but if they aren't eating solids yet - Pellet mashes only! (critical care by Oxbow is real good) No formula.
Guinea Lynx :: Hand Feeding Scroll down ot the section about young pups. I don't know if the blue lips would be a cause of the formula or not, I'm not experienced enough and have never hand-raised pups.
Good luck, I'll be keeping your little pigs in my thoughts.