Ive just checked this with my legal guy and technically anywhere that there are two ladies working will be regarded as a brothel. It doesn't matter if it's a shared apartment, a clients house or a hotel room ect.
Therefore if you are looking to book a foursome with a duo then technically speaking where ever this meet takes place will be deemed to be an illegal brothel.
Crazy law.........
Only you guys can decide if the risk is worth it x