Hi, just read your post. There was at least one line of Mulhollens/Mulhollands that immigrated to New York in the late 1700's. The father was John Mulhollen, born in Belfast in 1734, wife was Christina. They had 8 children which seems that they all eventually immigrated to the US but at different times. My line is Charles Mulhollen, born in 1765 and immigrated to NY with his son Charles Jr. in 1796. I think the elder Charles died in PA in 1810 as did the father John. There is a Charles Mulholland in Monroe Co Ohio in 1820, who had a daughter, Mary, born in 1824 and she married my ggrandfather, Thomas King.
One of Charles's brothers, Daniel lived in NY state for awhile and eventually moved to MI. John, the oldest son, married in Bucks Co, PA and moved to Painted Post, Steuban Co, NY where he died. James, the 2nd son, died in PA and William died in NY. Two of the daughters were in the US, one in PA and one in NY. The last daughter I don't know where she went or if she died before the rest of the family immigrated.
I would be glad to share information with you if you like. I don't have anything past the mid 1800's of the Mulholland line.