I think no one has really more proof of owning the shares. Luckily with burnside we have an exchange owner that did not run and is still communicating so he would help us with backing our claims for sure.
Sorry, responding to an old post, but I figure it's still relevant.
I don't have all the servers anymore, but I do have CSV's of trades for all accounts that could be used to show ownership prior to BTC-TC's closure. Labcoin may potentially counter that you could have sold them when they moved to an alternate exchange, but should anyone need their BTC-TC CSV I am happy to assist as time allows.
Cheers