The birth details for Olive seem wrong. She is shown as born in the parish of which her future husband would later be parish priest, whereas her father is from a long-established Lincolnshire family. https://www.wikitree.com/wiki/Irby-1 has different birth details.
Interestingly, Paul Aubert Irby's "The Irbys of Lincolnshire" has no mention of Olive as a daughter of John Irby and Rose Overton, mentioning only Bartholomew, Peter Kenelm, Edward and Mary.
That's odd, because Olive is mentioned in her mother's will
https://archive.org/details/bulkeleygenealog00jaco/page/19/
I was going to post the same thing.
The Bulkeley genealogy : Rev. Peter Bulkeley, being an account of his career, his ancestry, the ancestry of his two wives, and his relatives in England and New England, together with a genealogy of his descendants through the seventh American generation / compiled by Donald Lines Jacobus. by Jacobus, Donald Lines, 1887-. Page 19-20. [https://archive.org/details/bulkeleygenealog00jaco_0/page/18/mode/2up Archive.Org]
Looks like birthplace was Kirton in County Lincoln.
She’s named as Olive Irby of Lincolnshire in Cambridge Alumni.
https://archive.org/stream/alumnicantabrigipt1vol1univiala#page/250...
It looks like Paul Irby's book is deficient, then. Olive would have been 11 when Richard Buckland's will was probated in 1558 (and her sister Phoebe, 9); so it would be very strange that they had no mention in his will if they were his children. If they were children of her third husband, Richard Beawe, then Olive would have been under 20 at the time of her mother's death. While it's not impossible that Olive could have married Rev Bulkeley and had children by that time, it would be unlikely. The implication (although, as noted above, not stated) is therefore that Olive and Phoebe were Irbys.
It would be good to clear up Olive's birthplace, though.
“ The Anglican parish registers exist from 1555.”
https://www.genuki.org.uk/big/eng/LIN/KirtoninHolland
So if she was born there say 1547, there isn’t a known existing record.