I live in Hungary and my grandfather was Zelei. We have a plenty of relatives in the east side of the country, called 'Alföld'. There is a similar thing here as facebook, I checked and I found 707 Zelei's on it :) It's called iwiw. May you should connect and write to the members, maybe somebody knows st. Sometimes members are creating groups, there could be one for Zelei's, too :)
Here is a datebase. I found things from the 15th and 18th century.