My greatgrandfather was Felix Koscinski, born 1883 in Paleschken near Pestlin, district (Kreis) Stuhm in West Prussia. At least one of his brothers went to the USA around 1900 but I don't know his name yet. Their parents were Johann Koscinski and Maria born Ronowska. Maybe there are some informations about these persons in your document on "The Koscinski Family Association" ?
If you are interested in some informations about the origin of the name Koscinski I can send you a copy of an article about it.