My wife and I are going to visit her family for the first time since we got married a month ago. My MIL previously stayed with us for two months, during which time I got to know her really well and became really close to her. I really love my MIL and feel perfectly comfortable calling her "mom," however...

I barely know my FIL. I met him twice, each time only for a few days. Plus, he's kind of an asshole and I really don't like him very much. I would feel extremely uncomfortable calling him "dad."

Is it okay for me to call one of them "mom" and use the other's name? Or is this an all-or-nothing situation? I don't want to hurt anyone's feelings or upset anyone.