I was trying to render the word documents attached to the Mail Merge Templates with Merge fields in the code(Apex class). I was hoping Salesforce would be having some API similar to Messaging.renderStoredEmailTemplate() for Email templates. But unfortunately i could not find any.
I am trying to avoid using Mail Merge & Extended Mail merge just because they have lot of browser compatibility issues and they are currently not supported in lightning. I don't even want to go for any 3rd party tools like Conga.
I am basically trying to implement Mailing & bulk Mailing features in Salesforce on my own. Can someone help me in this regard?