Currently, I can design a custom form to say 'Make this field required' or 'Let this field be optional'.
I would like the ability to say 'This field is required, ONLY if this other field is option X or Y.'
Example: An order form for a laptop purchase, where the user can:
Buy a basic laptop (dropdown) and order one of three optional accessories (3 text fields)
Buy a fancy laptop (dropdown), and be required to specify the brand name for the same accessories since they're now included (3 text fields)
I realize I could work around this by having two identical sets of fields, then displaying each one differently depending on the Basic vs Fancy choice, but this leads to incredible duplication of fields for any kind of lengthy set of choices.