So we survived. I called MIL and told her what time to come. Turns out DH had called earlier so she was ok with the time. She kept grilling me on food-did I have enough of X, should she bring Y, was my mom making Z? Then she asked if we had a few things necessary for serving the dinner. She has eaten here before. I told DH that her treating me like a child was driving me nuts.
Then she decided to go around me and call my mother. Item Z was essential, but my mom can't eat it do to allergies. My mom and I were going to make a small batch that she could eat. Luckily I made it larger as T minus 2 hours MIL decided to not bring her version. She offered to whip up more food. I had already turned her down and knowing this my mom politely turned her down as well.
We coordinated oven space for everyone with minimal stress. My family helped with the serving as they were placed in spots they could easily moved from. The food was good, my family helped with clean-up and I had the house quiet by the time DD went to bed.
Now I'm waiting to see if my tablecloth can be saved.