Muliple Related FK in EF Core - postgresql

Question

I have segmentation class which have some price range, related office and route. I want routeCountyMap table with route and county related but I can only assign county once per segmentation.
E.g. for 200-400 segmentation has A and B office and A office has E,F,G routes; if there is X county with F route, there won't be able fore 2*00-400 segmentation*. My codes are below, how can arrange it?
public class segment
{
[Key]
public Guid segmentId { get; set; }
public string name { get; set; }
public Guid organisationId { get; set; }
}
public class office
{
[Key]
public Guid officeId { get; set; }
public string name { get; set; }
public Guid segmentId { get; set; }
public segment segment { get; set; }
}
public class route
{
[Key]
public Guid routeId { get; set; }
public string name { get; set; }
public Guid officeId { get; set; }
public office office { get; set; }
}
public class county
{
[Key]
public Guid countyId { get; set; }
public string name { get; set; }
public Guid cityId { get; set; }
}
public class routeCountyMap
{
public Guid routeCountyMapId { get; set; }
public Guid routeId { get; set; }
public Guid countyId { get; set; }
public route route { get; set; }
public county county { get; set; }
}
public class user
{
[Key]
public Guid userId { get; set; }
public string name { get; set; }
}
public class routeUserMap
{
[Key]
public Guid routeUserMapId { get; set; }
public Guid routeId { get; set; }
public Guid userId { get; set; }
public route route { get; set; }
public user user { get; set; }
}
DB diagram