Limit signature fields to certain digital IDs

I'm attempting to create a PDF of a municipal grant draw form. It's a simple form consisting of 1 page of financial information, and a page of 6 required signatures. Before cutting a check, the draw down form needs to be signed by 6 individuals authorizing various aspects of the draw request (compliance, code enforcement, controlling, etc.)

One of the requirements I have is that only certain "people" should be able to sign specific signature fields. For instance, a number of accounts payable clerks can sign off on the initial signature field before sending it on its way. They should not, however, be able to sign the controller's signature field.

In my investigation, I haven't found any capability to limit valid digital IDs for a specific signature field. Does anyone know whether this is a possibility?