There would only have been a baptism record (not birth record) for Margaret Ann Allen as she was born c1852 (probably just missed being in 1851 census with her parents).
Unfortunately the local Presbyterian churches do not have any record of her or her siblings. Aghadowey, Crossgar, Killaig and Macosquin have all been checked, Ballylintagh doesn't have any existing baptisms, Ballylaggan does have older baptisms but is Reformed Presbyterian. Ringsend and Dromore are too recent.
Therefore, unless an old Family Bible just happens to turn up somewhere then you will not get a nice tidy record showing Margaret's date of birth and her parents.