Storyline 3 project gives error while Exporting translation to Word gives "Exception has been thrown by the target of an invocation'

I have split my project in to 3 separate pieces and outputted 3 separate translation docs. Obviously some of the items repeat - from the master slides.

Do I need to try to combine them now into 1 word document?

How do I do this? - will it cause issues with stuff being imported back into the original file?

Or do I keep the 3 docs separate and load them back into the original file one at a time? 

Obviously with removing scenes when separating  the project - they all ended up being scene 1, 2, 3 in the original they are numbered differently - will this cause an issue with reimporting the translation - the work around does not explain how to get the translation back into the course.