Not necessarily.
If we go with the Themes idea, we could isolate the characters we think are important (obviously the ones I named already, but there's other important characters), we could make it work.
I think the Reed brothers are important, given that they seem to be the main foes for a good chunk of the game. Or at the very least, ~Theme of the Black Fang~ would work.
As I see it these are the themes we'd have.
~Theme of Lyndis~
~Eliwood~
~Hector~
~Black Fang~
~Morphs~
~The Twins~
~Nergal~
I'm also thinking ~Theme of Nino~ might work too.
that makes 8 tracks. Now there can be combinations of sources in these if need be, but on the whole I think 8 would be good. Maybe even 9, since what's a Fire Emblem album without a mix of the franchise's main theme?