Pad thai is one of my favorite dishes! I love that you made your from scratch. I'm not sure what happened that your DIL doesn't like it, but it must have been something traumatic. Throw some spicy sauce on there for your wife next time and you'll be good to go!
I've come to really like Pad Thai, too. I liked the restaurant's version better, though. Mine definitely needs more heat, but not a whole lot, and more peanut sauce.
I think the DIL is just picky. Which is why she's so skinny. She just doesn't like a whole lot of different foods. Since her oldest sister is like that, too, it's hard to tell if she's actually being healthy or not. She's got some kind of digestive problem she's never fully diagnosed either, that went away while she was pregnant, but now it's coming back I think. I suspect she doesn't like the texture of the rice noodles, either.