Change "Email PDF" default email link

[dodom2]

I have the sales pack extension. I have added "Vendor" entity and created a relationship in the the "Sales Order" module. So I need to change the default email address and "parent" field to vendor and the vendors email address. Can someone help on where I would do this as Im not having any luck with it.(SCREENSHOT: https://prnt.sc/rzeif5 )