Ally destruction by reducing influence zone

[rogue-spectre]

When building town centers near an ally zone, the influence zone of our ally is reduced. If one construct a lot of buildings, eventually the town center of the ally can be surrounded by one's influence zone, as a result one can destroy it's ally without fighting.

I can imagine the following solutions :

• Enable building into allies zones. ( could be nice to try to rebuild - strengthen ally position / force balancing in case of diplomaty - market )
• Add an option to disables influence zones
• Ally existing zone is dominant ( building near a ally influence zone won't reduce the influence of the ally )