Thanks for the info on the Old Believers. However, I did read somewhere that they had more or less assimilated into Latgale society. Which explains why they did not leave when Latgale became territory of the Russian Empire. As Old Believers did elsewehere - some of them fled from the Tsar all the way to Mexico.
As should already have been clear from my German link, Neu-Letgallen may have been an estate or soem castle at the beginning, but it was definitely used as the name of a village in the area. Jewish material on the web:
http://www.jewishgen.org/yizkor/Pinkas_latvia/pinkas_latvia.html
pgp