Set action behavior based on another control.

I'm trying to set up a data entry form with the following:

I have a radio group with two options.

Organization

Person

Underneath I have five text boxes

Organization Name

First Name

Middle Name

Last Name

Suffix

If Organization is selected the textbox Organization should be required - all other textboxes disabled (not hidden).

If Person the textbox Organization should be diabled - all other textboxes either required or optional (suffix and middle).

Is this allowed? - it should be - can someone suggest a workaround (or multiple workarounds)?  The workaround needs to be in a way that makes data entry fluid.

Thx