Could not find a Townland called Ballydonnellan but one called Ballydonnelly in Duneane Parish not that far from Randalstown.
Lewis Topographical Dictionery of Ireland 1837 edition indicates that the Ancestor of John Dickey of Low Park Cullybackey started the linen industry in the Ahoghill Parish.
Perhaps the John Dickie that you mention was the one indicated in Lewis's Topographical Dictionery.
My gggrandfather Samuel Dickey was living in the Ahoghill Parish in 1850 and he named his eldest son John probably indicating that his father was called John.
Do you know the names of this John Dickies children?