The quick version of our question: is there a way to reassign tickets in the "Email" channel to a non-email "Contact" without changing the ticket "Channel" to "Phone"?

Context: My property management company uses Zoho Desk to manage email requests from tenants. Usually, tickets come directly from tenants, but occasionally they instead come from third parties (like caseworkers) who handle communication for multiple tenants.

Since the tickets come from third parties, they are initially tied to an "Account" and "Contact" associated with the third party. We'd prefer that the tickets instead be associated with an "Account"/"Contact" associated with the specific tenant who is the subject of the ticket. 

The issue arises when the tenant's "Account" does not have any "Contacts" with associated email addresses (if, for instance, we only have a phone number on record for the tenant, we would have a single "Contact" entry with a value in the "Phone" field). For these tenants, when we edit the ticket to select the appropriate "Account" and "Contact", the "Email" field becomes blank. As a result, Zoho won't let us save the ticket unless we *also* change the ticket "Channel" from "Email" to "Phone".

Is there a way to change this behavior, so that we can edit the ticket "Account" and "Contact" without also having to change the "Channel"? It's just a couple of extra clicks, but those clicks do add up over time.