[SalesForce] write if/else condition for mail merge template

Matt is right. Oppty is treated as a special object in standard mail merge for the purposes of generating proposals or invoices. You could potentially roll-up your detail data into fields on the parent object, but otherwise I'd recommend Conga.

Wrap the conditional merge field in quotes, e.g., { IF "{ MERGEFIELD Contact_custom_field }" = "Anonymous" "anonymous " ""}.

I've managed to set up a complex merge document with 20+ IF statements that successfully generates a nicely formatted 20 page Word doc that includes/excludes entire sections based on them.

The issue I am now grappling with is that IF statements are output as fields in the generated document (vs the simple mergefields which are converted to a text value as expected). This is particularly problematic where the ELSE output is blank ("") since it leaves the whole section in the document (though, to be fair, at least it is somewhat hidden behind an empty paragraph mark).

I can then either protect the form so no one can toggle to view the field codes or convert the Word doc to a PDF. My preference is to have a 'clean' merge document from the start so that I don't have extra steps to perform.