In a template can you pre-assign signature fields by email address instead of generic sender1, etc?

I am trying to create a template that has potentially a specific set of 50 signers.  Can I use the signature field and use text tags to assign the email addresses to specific lines?  or is there another way to do this?  If when sending I need only a few signatures, would I be able to delete the unused fields before sending?  How would I set this up?