You could pass a pointer from either:
1) the FormView window, or
2) a class or structure containing your data members,
to your dialog box when you create it:
1) CDialog MyDialog(CWnd* pMyFormViewWnd);
2) CDialog MyDialog(CMyClass* pMyClass);
Then, within your dialog, you can use the pointer to access either the FormView's methods or your structure:
1) pMyFormViewWnd->SetCustomerName(sName);
2) pMyClass->SetCustomerName(sName);
Alternately, you can POST messages to the FormView window itself.
pMyFormViewWnd->PostMessage(WMU_USER_SELECTION);
Hope this helps.