... What does it mean that her father was a Land Steward ...
As far as Ireland back in the 1800s is concerned, most land / estate was owned by the relatively few and leased to tenants. Many substantial owners employed land stewards, often in their own prolonged absence, to manage their lands, ie. to look after their asset and maximise any income.
If it was a large estate, the land steward would have had several people reporting to him, for example gardener, gamekeeper, workmen to repair fences etc. The Land Steward would have paid their wages and kept account of their work. He would have kept records of livestock and crops.
Another important job, whether a large estate or disparate pockets of land, was to collect the rent from the tenants (farmers and just householders living in houses). It was this aspect of the job that could become contentious!
PS. the RootsIreland website has a church marriage for a Robert Creighton to a Mary Hamilton in County Monaghan in 1830, in the circumstances I suspect this may be the same couple and that they had two marriages, one in Scotland, one in Ireland. The record is pay to view but be aware that it may offer up little information of assistance, for example, the location of the marriage and where the bride and groom were living. Where the bride and groom were living is precisely just that, it doesn't necessarily mean any ancestral / longer term association. Your choice.
PPS. lots of Hamiltons in Monaghan here in these records of occupiers of agricultural land, not so many Creightons (though they may be under alternative spellings, I didn't check):
http://titheapplotmentbooks.nationalarchives.ie/search/tab/index.jsp
