Where does the surname Donasewicz originate from?

Most likely Polish. There are very few records with this name. The lone Donasewicz in the passenger lists was born in Poland.

I think you just answered your own question. Eastern Poland and Lithuania were treated as though one land for most of the last 400 years. There was free movement between the two areas and names crossed over because of the intermixing of the Slavic and Lithuanian languages. If you know the family was from the Vilnius area, and knowing that Donasewicz is a patrynomic name, it's quite reasonable to believe the records you need are in the Vilnius area. The name itself is fairly generic and could pop up anywhere in Poland with no relationship between this group here and that group there. Names don't have many ties to a specific piece of property, but they do have ties to groups of people who have some things in common. So follow the paperwork and see where it leads you.