How to prefill a multi-select Zoho CRM field in Zoho Sign template

How to prefill a multi-select Zoho CRM field in Zoho Sign template

Greetings, 

I have a few multi-select fields in Zoho CRM that I woud like to prefill a template in Zoho Sign. Placing a prefill Text field on the template in Sign shows the multi-select field when trying to link fields, but it doesn't populate the box and get an error. Is there a way to do this? It can be done with text tags, it seems, on a merge, but there are limitations on the mail merge that make that not a desireable route for us. 

Thanks!