I don't think the linked content controls will be the way to go. They definitely could be used for this feature, but they problem is they are a bit cumbersome to insert. Part of the reason I settled on [n] rather than the more traditional %FirstName% is because it can be typed fluidly, which is a big part of my groove.

A combination of your, and Greg's suggestions gave me an idea though... When my GUI dialog opens and collects its data, I'll have it also assign some custom Document Properties such as
FirstName = Jon
LastName = Doe
and so on.

Then a second macro can be run for an already in-process report. One click of a button can do all the changes (find [n]; replace with FirstName) and so on.

So I guess this forum topic/idea is a dead end. Thank you guys again!