Mailing List Archive

Is there a template or module that can change another page ?
Simple Scenario:
I have a page that gets changed.
As it is being changed, I know that templates and modules are
transcluded/called to
resolve what the page should look like, and what form will be stored in the

Let's say the page "Petition//Will_Of_The_People" is a list of names
signing a petition (Call it "Will Of The People".)
Someone (Call them "Pat Chris") edits it and adds the same template or
module or something like that to the page.
Is there any mechanism whereby I can mechanically/programmatically update
the page named
Category:Pat_Chris/Petition and specify what line to add to it, saying they
signed the "/Will_Of_The_People" petition?

Thanks in advance,
Dave Whitten