Absolutely!
Not sure how far to go here, but can say, have done that before, got into activities that have been touched on here and a great time was had by all because we all went into it willingly.
As a discrete exhibitionist (contradiction in terms) I enjoy sessions with others present, whether mistresses, subs or both. Really adds to the excitement of it all.
Eagerly looking forward to my first session at the Fortress later this week and made it known others are welcome to watch and/or participate.