[TYPO3] dynaflex in tt_content only with templavoila?!

[Andreas Jonderko]

Hi typo3 friends,

I'm trying to use dynamic flexforms with tt_contents, i want to show the 
flexform only if someone choose flexible content element as content 
element.

so i try this:

doesnt work 
$TCA['tt_content']['types']['templavoila_pi1']['subtypes_addlist'][$_EXTKEY.'_pi1']='pi_flexform';


This one works, but i dont want to overwrite it...

So how to add something it this one?
$TCA['tt_content']['types']['templavoila_pi1'][showitem] ??


Next question is on dynaflex ... is there maybe an extension which uses 
dynaflex on tt_contents? how to use it?

best regards
Andreas Jonderko