Q: Master slides and placeholder content

I'd like to construct a presentation where I have a number of different master slides that all rely on slightly different configurations of placeholder content.

For example:

Master Slide 1 relies on placeholders <1>, <3> and <10>

Master Slide 2 relies on placeholders <1>, <6> and <8>

Master Slide 3 relies on placeholders <2>, <4>, <7> and <9>

etc etc

I would like to be able to enter in ALL the placeholder copy (ie. placeholders 1-10) for a project and then cycle through Master Slide configurations that show those various configurations without having to fill in the copy over and over again.

Problem is, if I look at a master slide that relies on placeholders <1>, <3> and <10>,  Keynote will forget the contents of <3> and <10> if I cycle to another master that relies on <1>, <6> and <7>.

As a result I'm constantly re-entering placeholder copy as a function of cycling through different master variations of layouts.

Is there a way to fix this so that each slide can contain placeholder content for 1-10 without having to include it in the slide's formatting?