Our database has a lot FKs that are integers. Some of them are required filed, some of them are not.  I have some questions:

1.      For required FK,  how do you write your own verifier? DevForce’s default verifier for required FK is always returns OK, no matter what. I tried to write a range verifier for the required FK, it always returns OK too.   How do you enforce the required FK?

2.      In edit screen, how do you fill the ComboBox of non-required FK? Add a null entity? Since it is not required, the user should be able to change the ComboBox to select nothing.

Any help/suggestion would be appreciated. Thanks!