Even if you are given trees/charts from previous researchers it is important to check details against official records as you work your way back, and to record the sources for all information you receive or find.
This is the full list of Pendlebury exact birth dates to 1901 from BL's index of registered births [URL last message]. Civil registration in the IOM wasn't compulsory for births until 1878.

Second forenames have been abbreviated.
First Name, Family Name, Day, Mon, Year, Parish, Father First Name, Father Family Name, Mother First Name, Mother Family Name.
Esther Ell PENDLEBURY 5 May 1879 Dou James PENDLEBURY Elizabeth MAINWARING
Ethel PENDLEBURY 20 Dec 1898 Dou John Tuck PENDLEBURY Mary BURGELL
Frank PENDLEBURY 27 Jun 1900 Dou John Tuck PENDLEBURY Mary BURGELL
George Tay PENDLEBURY 12 Apr 1896 Dou John Tuck PENDLEBURY Mary BURGELL
James Albe PENDLEBURY 4 Sep 1891 Dou James Albert PENDLEBURY Margaret STUART
John James PENDLEBURY 30 Aug 1891 Dou John Tuck PENDLEBURY Mary Victoria Ros BURGELL
John Willi PENDLEBURY 5 Dec 1895 Dou James Albert PENDLEBURY Margaret STUART
Leah PENDLEBURY 28 Apr 1893 Dou John Tuck PENDLEBURY Mary Victoria Ros BURGELL
Priscilla PENDLEBURY 24 Oct 1900 Dou Jabez PENDLEBURY Priscilla Ann GALE
Thomas Gal PENDLEBURY 17 May 1899 Dou Jabez PENDLEBURY Priscilla Ann GALE
............

There are these registered marriages [www.iomfhs.im/lawsons/LawsonBMD/Main_Site_index.html]
Marriage registration compulsory in the IOM from 1884.

Name, Date, District, Vol, Page, Spouse:
PENDLEBURY, Jabez 5 Jun 1898 D bra 727a GALE, Priscilla Ann
PENDLEBURY, James 8 Sep 1890 D onc 18 STUART, Margaret
PENDLEBURY, John Yuke(sic) 19 Nov 1890 D onc 18 BURGELL, Mary
PENDLEBURY, Matilda Martha 15 Oct 1889 D dsg 26a CHADWICK, George
PENDLEBURY, Nellie 30 Oct 1898 D bra 742a ADAMS, Charles Robert

The actual certificates would have a lot more information and can be bought from the IOM Registry: www.gov.im/registries/general/civilregistry/

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