Need accounting advice

[Vahur Lokk]

Hello!
I am getting into a strange business situation. My main business is 
freelance translation. Easy enough from the accounting point of view.
Now I am making a contract with a big client, organisation that does 
film festivals. I am going to do all the subtitling project management 
for them. At least double my current turnover + hassle with 
subcontractors and all that PITA.
This means that through the year will be few smaller (still big for me) 
festivals + huge one in the end of the year.
I just finished the first small one and i feel quite uncomfortable, 
because I would like to monitor project costs separately.

Can I organise gnucash so, that I create a separate file for every 
festival, using my usual account tree, do the project/festival 
accounting there, then, when everything is finished, import it into my 
main accounting file? This way I would have an overview of project 
profitability, cost control etc.

If this is possible, then what limits/problems I will have, eg. how can 
I handle situation if, for some reason, I need to present a balance 
sheet during one of the festivals and therefore have to do an import of 
"unfinished" festival file?

Wahur