As it turned out, it was all a lot of bluster.
Kate and Ron and their respective spouses and children went to Aunt and Uncle's house for Christmas Eve dinner. Kate made sure her son wore a mask throughout the evening and kept him farther down the dinner table to limit his exposure as much as possible. The girl who went to Hawaii also wore a mask at Aunt and Uncle's request.
Kate said it was a lovely dinner and there was no tension. Good news all around.