LOL that is a LOT of puppies, I am going crazy with 5, I can't inmagine 12..
I did the felt collars and it worked fine, you just have to be careful they don't get too tight. make sure mamas get those extra meals specially the one before bedtime, with a serving of whelping pudding or the calcium pill. Best of luck with the pups .. and again congratulations..also the scrambled egg every day is a must...