geodjango floppyform issue

Hi i am new to geodjango floppyform, i have some difficulty
i working on application where i need to restrict user to create point or line-string(route) withing certain geofence(city), so in short while user creating route map would allow to create point and linestring (route) in certain regien by keeping other part of map disabled ?
e.g
i want to make entry for bust stop as a point A
but while creating i want to restrict user so that point should be created in "XYZ" city region of the map only, it should not allow user to create any entry out of the bbox of XYZ city, is it possible ?
can someone please guide me ?
my map contain 100 such cities

No files, tests, or entry points are identified. First clarify whether the requested geofence behavior belongs in django-floppyforms or in the map/geospatial layer, then define how city boundaries should constrain point and LineString creation. Done should mean that users can create routes only within the selected city's region while other map areas are rejected or disabled.

Written by the indexing model from the issue text.