We have a custom field on the Purchase Header that holds the User ID that the approval should be sent to.
My thought is we need to create an approval request for a specific user (Approvals Mgmt Codeunit - CreateApprovalRequestForSpecificUser) but I wasn’t sure if anyone has done this before/ knows an easy way to hook into the base code.
I have done this and trust me its really complicated. Yes, its in the approval mgmt codeunit and you have to publish your code after the integration code and took me a while to figure this out, unfortunately I cannot detail out the entire code and even if I do it will just not make any sense.
I ended up using the Event Subscriber for OnAfterPopulateApprovalEntryArgument and just overrode the Approver User ID of the WorkflowStepArgument (which you can get using the WorkflowStepInstance.Argument)