Update June 15 2016: The next of kin still did not receive a reply.
A group of next of kin of MH17 victims send a letter at the end of January 2016 to president Poroshenko, Putin and Minister of Foreign Affairs John Kerry. In the letter the next of kin request to hand over satellite and radar data to the investigation team.
While Russia and the United States responded, Ukraine still did not respond (as per April 7 2016)
Response of Russia and US can be read in this post.
The next of kin requested the Ukraine ambassy in the Netherlands about the status of a reply by Poroshenko. They did not get a reply!