well, whoever wrote the navigation thingus did a thorough job.
they did what you had to do to make something that would handle most any normal situation.
but it's not easy to program!
I submit
1.
if you're happy with the navigation methodology and your app lends itself to having multiple, separate but similar navigation plists then subclass the navigation object and ask for the pageConfiguration key before returning results from one of several potential files.
2.
if you're thinking life could be simpler for your navigation programming, then I'd simply write a quick navigation component that exactly fits your logic and use that instead.
that's my take anyway, perhaps the navigation has some other sort of hooks already that I'm not familiar - I'm not an expert on it, but I've used it.