I don't have access to the Institute of Migration's services anymore but they are open to everybody for a year's membership fee of 15 euros (http://www.migrationinstitute.fi/netshop_e/
). I made a search on the online cencus records but came up with nothing. The info of these people might not have been transcribed yet. Another search in a few years could bring up something so don't give up!
All I can really say is that I'm quite certain Esa's and Brita's last name was originally Turpeinen since the other versions are not possible. Maybe this will help you a bit.