Your such a nice person to go though so much trouble to assure she is taken care of during her whelp. I'm concerned thou about her wanting to care for the pups properly do to her age, she's just a pup herself. It's important that you help get the family prepared and aware of what needs to be done just in case you are not there or available at the time she is whelping / having the pups.
You may want to do some research on what to expect with a young maiden. (meaning: first time dam/bitch)
I'm learning some new things here on YT myself , thanks Carmen
I do hope that the family is more careful the next time. Maybe having one or the other fixed would be a good idea.
Due date: You should go the date of the first tie. Be sure that you or someone is taking and logging her temperature. Below is what to expect with temp change.
Canine Reproduction Video and Book on Breeding and Whelping dogs by Debbie Jensen for dog breeders and Whelping Supplies needed to deliver puppies.