found this marriage: groom:Hugh Lafferty bride:Mary Black date of marriage:21 April 1845 place of marriage:Conwal,co Donegal could this be Sarah's parents??
Sarah Lafferty occupation:servant age:25 ship:California date:10 April 1873 departed from:Glasgow arrived at:New York passenger born in Ireland
Sarah Lafferty age 14 Mathew Lafferty age 20labourer ship:Emerald Isle date:13 Aug 1860 departed from:Liverpool arrived at:New York both passengers born in Ireland
I also checked Boston passenger lists but couldn't locate Sarah in them.These are more likely,especially the first one,as Adams,Mass where she married is on the New York border.Also,many immigrants from Donegal got ships from Glasgow which generally arrived in Derry before heading to the US.It is possible too that her birth could have been registered in co Derry if her parents lived near the border of Derry and Donegal as depending on parish it determines where a birth is registered.Hope this helps,Kim