Changing tile between cities?

[Mohreb]

Hi i am looking for a way to change tiles between cities (3 distence for both 10+ cities and an other at 2 distence between two smaller cities)
and if there is no way (i tried anything i fund in the interface in both cities) can at least someone tell how are square assignments determinated?

 

[Seulessliathan]

First city which gets access to a tile keeps all the tiles. If then another city expands, it can only get tiles which are not already owned by another city. So far switching is not possible. It has been mentioned in Suggestion thread.