Show specific contract and supplier site only on smart form, not on non-catalog request

Hi all,

On 12.1.3, is it possible to allow the use of a particular contract only on a smart form and not show it in the LOV for a non-catalog request?  Same question regarding supplier site--use a certain site only on a smart form but not find it in the LOV for a non-catalog request?

We have certain contracts and supplier sites with very specific uses that only a few users should be able to access.  No matter how we name the supplier site or what kind of training we provide, people still make mistakes and select the wrong contract or site.  These are all global CPA's within the same OU.  Can we restrict their use via smart form?  Is there another way to prevent the wrong people from being able to see and select the contract or site?