"It's more labor intensive than caring for a newborn--and with a newborn you have the expectation that the child will grow and become more independent." EXACTLY, and that makes it harder... as anyone with kids know, the kids stop taking naps.. So you live on even less sleep.. However once again it is doing what needs to be done...
Im sorry but even if her husband works 12 hour days, she could still work for a few hours at night when he comes home...
Perhaps I was raised differently... if your child needs something you work to provide it for them... you dont ask anyone to take care of your child... Sick or not...

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Be careful what you wish for.....