Something is wrong with spellings of surnames. Where have you gotten spelling Ruksnaites from? Lithuanians usually spell this surname Ruks^naitis. It mean that you may find different spelling in Ellisisland database: Ruksznaitis, Ruksnaitis, Rukshnaitis, Rukschnaitis, Rukschnait or simmilar. All depend on language was used for documents: Russian or Polish or German or Lithuanian or Latin (in church) so far. The second surname Lithuanians usually spell Mockevic^ius or Mackevic^ius. A letter c in Lithuanian sound as "ts". A letter c^ in lithuanian sound as "ch". So you may find different spellings too: Mockewicz, Motskiewicz, Motskiewitsh, Mockiewich.
Speaking about spelling Ruksnaites I wanted to say that such spelling is possible only for two and more girls (plural form). For example: Zita ir (and) Rita Ruks^naites (e with a dot on the top). According to Lithuanian tradition on surnames it mean that their father has a surname Ruks^nas (Ruks^nis, Ruks^nys).
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Regards.
Vidmantas.