Conditional Paragraph Tags?

[John Newman]

I need to produce two versions of the exact same textual content (a 
software manual), except one edition needs have some parenthetical text 
[e.g., "(A) Lorem ipsum ..."] appended to the beginning of each 
paragraph, heading, figure caption, and table title.

For example, one version needs the headings and paragraphs like this:

Heading Words
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi blandit 
elit vel leo auctor ultrices. Aenean ut arcu elit. Pellentesque ante ...

The other version needs the headings and paragraphs like this:

(A) Heading Words
(A) Lorem ipsum dolor sit amet, consectetur adipiscing elit. Morbi 
blandit elit vel leo auctor ultrices. Aenean ut arcu elit. Pellentesque 
ante ...

Since the appended version is a new requirement, I created one manually 
to meet an immediate deadline by making a copy of the whole FM book and 
adding the parenthetical element using Autonumber Formatting to the 
appropriate paragraph tags.

I don't want to maintain two versions of the exact same content (it's 
over 150 pages), so how can I do what amounts to conditional paragraph 
tags? It'd be great to somehow tell FM, "Use NORMAL-LAYOUT because this 
is a normal document." And then after producing a PDF tell FM, "Use 
FUNKY-LAYOUT because this is a funky document."  The solution is 
probably staring me in the face, but my brain can't seem to find the way.

Thanks!
John