I really can't imagine any alternative to a broken leg but surgery. Hopefully others will come on regarding a broken leg and can advise based on experiences. I'm sure it depends on the type of break, etc., but I know nothing about broken bones.
I know these little ones are so fragile, it would be so easy for them to be injured with small children, who are known to be rough being such a young age.
I'm sure he loves her to pieces but they will need strict supervision when they are together...well, at least util they both grow up.
She likely is not eating due to the broken leg and may be in pain.
Sending prayers for your pup and hope her recovery is successful.