A minor error for you, with call a slave to your room interaction.
With the 'Bring another slave to/to be f...' you a prompted to order your slaves to undress, even when both slaves are already naked (other interaction only prompt you when your slave is wearing some clothes). Also (for female/female slaves), when one slave is given the strap-on to put on, they also put on underwear, which renains on after the interaction has finished.