At present it is impossible to map dorms with private rooms

If you want to increase the possibility of booking, for example during the low season you can create special virtual rooms. Have a look:

1) Create virtual private room that would mirror your dorm room, for example if your Room 1 is a 6 Bed Dorm, create Room 1a that will be a 6 Bed Dorm and 1b that will be 6 Bed Private Room. 

2 ) In your backoffice, make sure that you have respective rooms for private room and dorm room, so in our example 6 Bed Dorm and 6 Bed Private.  

3) In MANAGE / ONLINE PORTALS map Room 1 with 6 Bed Mixed Dorm and Room 1a with 6 Bed Private. 

4) Don't forget to upload availability for one year in MANAGE / ONLINE PORTALS / SYNCHRONIZE so that portal receive your recent changes.

5) How to manage those rooms now:

It is very important to remember that if the Room 1 6 Bed Dorm will be booked you should instantly  block the the Room 1a 6 Bed Private. It has to be done manually and it shouldn't be neglected because it may lead to overbooking