Are you sure they weren't back home temporarily in 1871?
The NZ records have a marriage in 1887 [1887/1547] for Ellen Jane Keig & Charles Wesley Turner.
In 1891 [1891/1625] a William Keig married an Annie Elizabeth Keig! (A cousin? Perhaps Ann Elizabeth d/o William & Ellen bapt Ballaugh 6 Oct.1855?)

Do you know which of the children of William Keig and Elleanor (Ellen) Caley could have been the parents of NZ-born Ellen Jane and William? - Which would help find them.

Sue