How to change account that request is logged under

I am evaluating ServiceDesk Plus MSP for our ticketing system, and have come across one thing which is stopping me from purchasing the product straight away.

currently have a mailbox called servicedesk@company.com which we have configured in the mail settings.

And we have many aliases for each individual client/account
      client1@company.com
      client2@company.com
      client3@company.com

On occassion we have people sending emails through to servicedesk@company.com. If these requesters aren't in the system, it creates their requester account, and opens a ticket, but in the default queue.

I can see we can change the account the requester belongs to, but it doesn't update the original request (only subsequent requests)

How can I update the original request, to reflect the correct account? So that we can provide accurate reporting to our client. I don't seem to have any options to allow doing so. I have tried this on std requests with no technicians assigned or work logs added.

Please help..

Regards
Dale