On purchase agreement confirmation, pane on the right side of the window opens. I have setup the print management setting for Purchase Agreement (PA) confirmation to sent email to Vendor's Primary Email address. The agreement PDF is being sent to Vendors address as required.

But I want the email template body to be linked with this PA email. I have configured the email template in orgainsation email template and systems administration email template. Through some customization developer is able to attach/call the body of email template, however the placeholders in the body are not getting the values of relevant PA.
HTML of email body:
<p> Subject: Purchase Agreement Letter %PurchaseAgreementHeader.PurchNumberSequence%</p>
<p>Dear Concerned,</p>
<p>Kindly note that this letter is to give legal form to the agreement between %Purchase orders.DefaultDimension.LegalEntity% and the seller, % Purchase agreement.PurchName%; having Account ID: %VendorAccountID%; regarding the purchase of the listed items at specified price, in specified quantities, mentioned in the subject purchase agreement.</p>
<p>Both the parties to the agreement are bound to abide with the terms and conditions of the said agreement. Terms and conditions along with the copy of purchase agreement are enclosed within this email.</p>
<p>Thanking you.</p>
<p>%Purchase orders.DefaultDimension.LegalEntity%</p>
</p>
<p> General Information to Purchase Agreement:</p>
<p>%Purchase agreement.AgreementClassification%</p></p>%Purchase agreement.AgreementState%</p></p>%Purchase agreement.Currency%</p></p>%Purchase agreement.DocumentTitle%</p></p>%Purchase agreement.Originator%</p></p>%Purchase agreement.ParentPurchAgreementID_PSN%</p></p>%Purchase agreement.PurchNumberSequence%</p></p>%Purchase agreement.VendAccount%</p>
The placeholders are being shown as the text values instead of getting values from relevant purchase agreement.
I want to create a link between email body placeholders to the PA for which email is being generated on PA confirmation.
The same is required for PO, using Confirm Purchase Orders batch job.
Do not want to link this process to workflow/ workflow status.
Any assistance in this regard would be highly appreciated.
Thanks and Regards,
Talha