Hi Maria,
I have no idea if my grandfather had any brothers or sisters. I can only find him im Manhattan in 1902 when he married my grandmother.
His declaration of intent stated he arrived in NY in May, 1900, but I find no documentation to that effect.
Do you know where in Galicia he was from? My Bieliny is near Nisko and Ulanow. (on his paperwork, it was listed as Bielmike - not Polish, so I'm really guessing as to the village...)
He died in 1913, leaving 4 living children (I understand there were 6), and a wife.
There is a lady in Florida who has a line of Grzybowskis from NYC, even the same neighborhood in Brooklyn, and we can't connect up. I've written to Polish parishes, am now waiting for a response - it's been about a month - and I'll let you know if I find anything.

Good luck,

Grace