translationOf references lost after schema update

i've got a custom archetype with an imagefield defined as
languageIndependent.
unfortunately the customer already created lot's of documents when i
noticed, that due to a typo (or should i say: ArchGenXML ;-) the field was
not set to be languageIndependent (languageIndependent:"1")

simply updating and reinstalling the corrected productcode did not make the
image appear in existing translations.
what i usually do in such a case is updating the schema.

after updating the schema all linguaplone references got lost.

i know that this already has been discussed:
* http://www.nabble.com/Linguaplone-references-lost-t557187.html
*
http://permalink.gmane.org/gmane.comp.web.zope.plone.archetypes.general/2906

however, these discussions do not provide a solution for the problem.
hopefully this will do ;-)
(i hope i won't have to migrate (recreate) all the translations.)

if somebody already solved this problem or knows a way how to get around it,
or even has some code for this - please reply.

thanks in advance!
  fRiSi




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