Itzik Duchman came over was met by Louis Siscovtiz, 111 Madison St., NY NY.  Also a note holding for sister.  arrival jan 4 1905

1905 NY Census shows Minnie Siscovitz with Son Louis.

Minnie could be Itzik's sister.

Itzik could be Isadore or Itzak Dichner.  If so they are the Hartford branch of the Dichners, Mama's first cousing and would confirm that the name was DUCHMAN.

Searched NYC database for:
Any siscovitz or phonetic marriage
Louis Siscovitz the son looks like he died 1940
Any duchman or dichner marriage with phonetics

Need something to connect itzik duchman with isadore dichner
Need something to connect isadore dichner hartford branch with mama

Isadore Dichner naturalization-10113

It looks like Isadore Dichner came over in 1914 according to census records

Itzik Duchman came over in 1905

Looks like a dead end now.