[TYPO3-english] fluidpages - two 'fedext' based extensions possible?

[Felix]

Dear list

In my fedext based system I'd like to change completely fluidpage's setup.

Let's assume I have 4 different page-templates which I use for my 
pagetree. For one PIDinRootline (PID #20) I'd like to use a complete 
different set of fluidpage-templates in BE. On those particular pages 
Editors should not be able to choose standard fluidpage Templates but 
completely different ones.

I tried differnt ways to achieve this but nothing worked.

I tried to override the paths by typoscript on the particular page 
(PID20) in the TS-Template (and copied, edited files/folders of course):
> plugin.tx_fed {
> 	page.fluidpages {
> 		templateRootPath = EXT:myextension/Resources/Private/Templates/
> 		partialRootPath = EXT:myextension/Resources/Private/Partials/
> 		layoutRootPath = EXT:myextension/Resources/Private/Layouts/
> 	}
> }

I also copied my own extension in a second one - edited files / path 
etc. again.
In this way it seems the first included static template of the 
page-template has priority

And I tried to include both fluidpages.xxxxPATH in the root page 
template. But the second one with a condition:

[PIDinRootline = 20]
plugin.tx_fed {
  	page.fluidpages {
  		templateRootPath = EXT:myextension/Resources/Private/Templates/
  		partialRootPath = EXT:myextension/Resources/Private/Partials/
  		layoutRootPath = EXT:myextension/Resources/Private/Layouts/
  	}
  }
[GLOBAL]


But it did not work :(

Is there another way howto achieve completly different 
fluidpage-Templates for just some of the pages?

Thank you in advance
greetings
felix