Even if she is a single parent because the dad isn't there. So what? People get divorced because of abuse and maybe the man wasn't worth a dime. It should be obvious to the 'where's the dad' folks that she has a excellent family support structure to raise such fine girls when she's deployed. I just think he's dead personally.
And one more thing, maybe they're adopted like rogueyam said. Oh well either way, she's to be cogratulated. Have a great weekend indy!