1) It would be nice to have a unique checkbox value (i.e. selected) in a list of records for an object based on a combination of fields such that there can always only be one checkbox selected in that list of records. For example: if we have a situation where there can be only one active contact from the list of contacts for an Account. The below shouldn't be allowed.

2) Secondly lets say a user selects another contact as an active contact, there should be an option that would deselect all other active checkbox for other contacts as there can only be one active contact for an account.

It would be great if we could have these two options in the field settings of a checkbox field.