That depends is the sith a light side or dark side ? I'd like them to have the group get along
She loyal imperial, yes she will ds option if does not damage the empire and give her gain. Though anti-empire descions she, refarin from doing. She has died once stopping a space station weapons being abled to be fired on balmorra ls option. However in same game, she luached a republic cruiser into hyperspace into a planet to weaken a powerfull new enemy to empire. Which is a darkside option.
So if the guy is threat to the empire then she happily join in