Some research suggestions while I ponder your puzzle.
The master index to Ordnance Survey Memoirs of Ireland would suggest it beneficial to consult Antrim Vol 37 containing references to a Lockhart family (P37) and a Robert Lockhart (P 40 and 175) both Carrickfergus. These memoirs were compiled in 1830s so it is possible (but by no means certain) that these are connected to Ellen's parents. I happen to know Woodburn, as one of my late uncle's lived there and I visited with my parents quite often. I don't have a copy of that particular volume but you should be able to order a copy online from the usual sources.
The Tithe Applotment books and Griffith's valuation may show up Lockharts in the area and give you the all important Townland. Then if you're really really keen (and lucky) you might find your Lockharts in the Register of Deeds for Ireland. This is available online via FamilySearch (LDS) website and a free account, but exploring it is an extremely tedious business of which an explanation too long for this message. There were no less than 8 estates covering Carrickfergus Parish- Brice, Brytt, Dalway, Donegal, Kirk, Macartney, Saunders and Vesey, so you just might find a lease from one of them to a Lockhart (and I stress, it's a big might and only if they weren't sub tenants).
Have fun
Matt