I am making overnight potato rolls and have always used 2/3 cup of shortening. I was thinking that half butter half shortening might make my rolls even better. Will this idea help or hinder a yeast dough potato roll?
That should be fine. Potato and butter is a pretty solid flavor pairing! :) Know that butter contains some water (~15%) so you may want to adjust your liquid ingredients accordingly. That amount of butter contains about a teaspoon of water, so not enough to really worry about, but be aware. Use unsalted room temperature butter, and come back and tell us how it went!