while it doesN'T* specifically say eugene sullivan and margaret leary (maiden) name are her mother and father, i'm assuming that's the case since that info is usually on them.
two things occurred to me. one, it's always seemed odd that lizzie and emma called her maggie, although her name was bridget. what, to them all maids were called maggie, and so generic that you just call them all by the same name? if i were she, that wouldn't exactly endear the sisters to me, yet she genuinely didn't seem to mind.
well if her mother's name was margaret, no wonder! it's conjecture, but i could see lizzie or emma accidentally calling her by the name of their former maid in the beginning, perhaps them asking her if she minded, and her responding, 'oh no, me mum's name was margaret [or maggie], it'll remind me of her.'
another thing of note, who knew bridget was vain? she shaved about a decade off of her age. she was 26 in 1892, yet according to her birth year here, she'd have been only 17.
*edited so's i wasn't saying the opposite of what i meant