How can we make it possible to convert minor and large cities?

[Lonck]

Minor and large cities are the last two levels of cities. How can I make it possible to convert these two to castles? I managed to make it possible to actually put the building in and when put on construction queue all the other buildings disappear but the city doesn't convert and all the city buildings reappear and so does the convert building. Any help would be appreciated.

[Caesar Clivus]

General modding questions are best asked in the Mod Workshop section of the TW Center forums. Many more modders hang out there than here