If you need more info on the Ellerker family tree I may be able to help.
I'm part of the Ellerker of Ellerker family (as opposed to the Ellerkers of Risby). We have traced a direct line back to sometime in the 12th-13th cent.
Its not a very common name, spelling variations include Elleker. It originates from a village in East Yorkshire where my father was born. It is of Scandinavian origin, eller=alder (a type of tree), ker=carr=marsh.
Most Ellerkers now live in York, approx 30miles from the village.