You could have one model which selects all the fields you need from the PRN and present them individually as Summaries.
Then when the prn changes - assuming we are talking about re-positioning or re-sizing fields or things of that nature, once you change the templates the summaries would most likely still be OK. (Not so of course if you have calculated fields and change them from, say, numeric to character and things like that but I guess you will be alive to that already.)
Would that help at all?
If you had Monarch 9 Pro I would imagine that you could also stay with the separate model idea (if summaries don't work for you) but create one master model that grabs everything you need and then have other model that are subsets of the master model using the object linking technology.
A STRONG link would mean that the subset models would automatically change with the master model changes.
A WEAK link would require an update action to be performed but would then perform the update with almost no user effort other than making the update happen and saving the result.
My guess is that Object Linking would give you exactly what you need by one method or the other - but you would need the Pro version available to set it up.
Beaten to it by Bruce as I typed!
Brent - yes the summaries should be able do what you describe in conjunction with projects but ideally that would make use of Project Exports which, as I recall, are a Monarch Pro feature ...
It's not that you can't set everything up with the Standard product but that it would be easier to get the various exports exported quickly and efficiently with the Pro version.
(If I understand what you want correctly.)