Hi Gary
The Millikens I have found are listed on the 1861 census in England. All of the following were born in Ireland but are registered in Liverpool under the surname Milligan. I know from other records that this is may be a variation on Milliken as my GGfather was William John Milliken and is on the list age 17.
April 1861 Census 10 Duckenfield Street Liverpool
James Milligan, 63, Bootmaker
Ann 58, Wife
Ellen 25, Dtr, Dressmaker
Mary 19, Dtr, Dressmaker
William John 17, Son, Bootcloser
William (married) 27, Visitor, Tailor
John Harvey 22, Lodger, Bootmaker
William John Milliken 9born in Belfast) married Mary Williams in 1863. I believe she is listed on the 1861 census at 38 Duckenfield Street. I checked records in Ireland without much luck. The connection to James Milliken of 44 Cromac Street looked to be good but as yet I have not managed to confirm it.
Graham
Graham