Karen
I am sure you know you need to backtrack from yourself collecting documents on each generation. You can not proceed with the research into the "old country" with the research until you find a precise place of birth for Mary aka Maria.
You might want to start in the church the children were baptized in.
KMETZ in Slovakia's phone book
http://www.zoznam.sk/hladaj.fcgi?co=telzoznam&s=kmetz&am...and KMEC
http://www.zoznam.sk/hladaj.fcgi?co=telzoznam&s=kmec&...Take a look in
www.ellisislandrecords.org Maybe you can find their arrival manifest.