the first time I heard about this ,I think there are none ,but if you choose the tournament where they play 9 people total ,then you can go with friends at the same table ,you can do it on any poker room
There are what's called 'home' games on poker stars. You can create your own table and give the password to your friends. When you are in the pokerstars client look at the bottom right of the screen and click on 'more'. then click 'home games' Nobody can join your game unless you give them the password.
The question is already answered but I would like to add up that there are many home games at Pokerstars where you can join them if you have the password and play against smaller fields. Some of them are with play money and some others are with real money prizepools.
Also many Twitchers have their own home games!! Have fun!
At Pokerstars there is the possibility of creating your own room with various parameters of the tables. You can give the room name and password access to it. Pass the password to friends.