In some of our 4 Player games creating a "Team" may be necessary.
Biska grants the user the possibility to choose his Team mate but with some limitations, in detail:

When the first Player reserves an empty seat in this type of games he gains control of his Team mate's seat as well (we can define him conveniently as the Team Leader). 

Clicking on this reserved seat by another Player equals to asking permission to the Team Leader to take that place to become his Team mate. The Team Leader may then decide to accept or refuse the request of the Player but he will be able to do so up to 4 times on the same table. After the 4th request is denied both seats will be made available again for other Players and the Team Leader will be banned from that table. 

This is to avoid tables being blocked by malicious users.  If a Team Leader accepts a request but then decides to leave the table before the game has began (the other Team wasn't composed yet) his Team mate will become the Team leader and the same procedure above will apply.