Rewrite forwarded email headers in EXIM to avoid strict DMARC/SPF block ?

We have employees that are setting up email forwarding addresses that don't always work. The reason is, for example, a financial institution will use strict DMARC rules that will cause the emails to be rejected at the final destination gmail account. So we have concluded what we need to do is rewrite the header of the email as it passes through our intermediate EXIM mail server. The question is, how do we go about doing this? So currently. a forwarded email's from headers would typically look like this if it were to be received: From: "FirstName LastName" reception@removed.tld Reply-To: johnsmith@removed.tld In our example, on our EXIM server our user made a forwarding rule to forward annaclark@ourcompany.com to annaclark@gmail.com And we are looking for a way to set something up on EXIM to automatically change the from header header to the following if an email is being forwarded: From: "FirstName sLastName - reception at removed.tld" annaclark@ourcompany.tld Reply-To: johnsmith@removed.tld *If there was no 'Reply-To' specified in the original email, set the 'Reply-To' to the original 'From' address. How would we do this in our EXIM config? Thank you in advance. Sincerely, Mike