namespace DocuMed.Domain.Entities.City; public partial class City { public static City Create(string name) { return new City(name); } public University AddUniversity(string universityName, string universityAddress) { var university = University.Create(universityName, universityAddress, Id); Universities.Add(university); return university; } } public partial class University { public static University Create(string name, string address, Guid cityId) { return new University(name, address, cityId); } }