Templates to Replace Existing Functions

I want to replace functions like create>proposal and create>invoice with my own templates for those functions. Of course, I want to keep existing functionality. So, if the function currently creates Accept/Reject buttons for recipients, I’d still want that. Same thing if the system displays whether the document has been opened or not.

This is similar to the Set Default Templates post. It is marked as completed, but I don’t see the functionality I described. BTW, in another post I’ve requested the ability to have multiple templates for functions so, for instance, a different invoice template would be used for homeowners and corporate clients.