Sadly, my girlfriend and I will be leaving Switzerland in a few months and we need to begin moving forward with plans.

We currently share a 3BR apartment with one of our colleagues (it is used as a "WG" wohngemeinshaft or shared student apartment). However, when we signed the contract, the landlord only put two of us (my girlfriend and I) as signees of the contract, and our third roomate was only listed on the text on the back of the contract as the "third tenant". Therefore, if my girlfriend and I move out, it is not clear what the process is. All three of us would like our third roomate to be able to keep the WG under his name and possibly get one or two new occupants.

We are planning to write a letter to the landlord and ask for them to send us a new contract with him listed as the primary tenant, and hopefully since he is already listed on the contract as a tenant (but not a signee of the contract), this will not be a problem. They already have his salary/employment information, copy of his permit, etc., from when we originally applied for the apartment, but we will certainly send updated copies with the request.

My question is if anyone has already been through this process of transferring the contract to someone else, and any roadblocks you ran into, and how they were resolved. In particular I am worried that if I approach this situation with the landlord the wrong way, they might decide to kick our third roomate and find new tenants (and would this be within their rights?).