Who did the sisters come with to the US? You never mention an adult.
Perhaps the name is sp. LACKOVIC, sounds like lochkovich. There is a record of a Kata (Kathy, Katherine) arr w/3 children Oct 3, 1908 aboard SS Pannonia. They show up on the Detained List reason tel. $ (needed to telegraph for money) disposition to husband, Braddock, PA.
You can find them by going to web sitehttp://home.pacbell.net/spmorse/ellis/mm.htm
Enter Oct. 2, 1908, frame number 298 then enter. They are line 7.
They can be found on regular ship manifest enter Oct 2, 1908, frame no. 353 line 1,2,3 and 4 children's names Karlo (male), Maria age 4 and Jana age 11 mths.
If you have more info about them it certainly would help