Slizauskas of Maybe Lithuania

For many years my great grandparents have not been easy people to find. Joseph Slizauskas, there are variants on this name and his wife Antosas Ubicente, even more variants arrived in Middlesbrough during the late 1800's Joseph went to work as a furnace worker at the docks, and from what family have told me Antosas was a sort of Au pair at the time. They met and married in 1901 at St Marys Cathedral in Middlesbrough. They lived at various addresses those being Stockton Street, Cleveland Cottages, Lincoln Street, and George Street. There were 10 children in all, my grandmother being born on the 28th March 1908. Also Antony, Francis b.1906, George b. 1911, Helen b. 20th May 1915, Joseph b. 1902, Margaret b. 1912 Michael b. 1903 and William b. 1917. There was a child Maria that died in 1905.
From stories told to me long ago by my grandmother, life was a trial. Her father was a big man of over 6ft. He was an amazing musician, play the accordion, and could stretch the whole thing across his chest with no bother. He had also an amazing singing voice. But he was sometimes a cruel father, who wealded the leather belt on many occasions. My grandmother remembers being the translator for her mother who dying in the 1960's never learnt to speak English. When Joseph died, the family must have been in dire straights. He died sometime during the flu epidemic in and after 1918. This is something any day now I will get an answer to after 18 years searching. I do not even know where he is buried.
I have all the birth certificates, marriage certificates of my great grandparents, but it gives no clues to where they actually came from originally. There doesnt seem to be any ship that has either of them as a passenger. The story is told in the family that Joseph wanting not to get recruited into the white army ran away!!!
Out there somewhere is more family in the UK, I have managed to find one cousin Margaret, but beyond that nobody!!
So if you know of or can help with this name and where it comes from, please fo write to me. It would be wonderful to hear from anybody.