private void DeleteCreditor()
        {
            if (SelectedCreditor.CreditorId != 0)
            {
                Creditors.Delete(SelectedCreditor.CreditorId);
            }

            FilteredCreditors.Remove(SelectedCreditor);
        }
        private void NewItem()
        {
            CompanyViewModel.Clear();

            if (_SelectedCustomerType == CustomerType.Creditor)
            {
                SelectedCreditor = new Creditor
                {
                    Client = CompanyViewModel.Client
                };
                FilteredCreditors.Add(SelectedCreditor);
                CompanyViewModel.Client = SelectedCreditor.Client;
            }
            else
            {
                SelectedDebitor = new Debitor
                {
                    Client = CompanyViewModel.Client
                };
                FilteredDebitors.Add(SelectedDebitor);
            }
        }