An example of the change of date due to change of calendars the Birthday of my Grandfather. At home in England this was always treated as 14 Jan 1868. But in Poland (or in Russia) it was 30 Dec 1867. Therefore, note that in different countries there may be different calendars. It should be simple for a Jew to swap between them, being used to swapping dates for work and for play and with some families keeping Yahrzeits in the one system and others in the other. But I forgot it when searching in Poland.
From: main@... <main@...> on behalf of jbonline1111@... <jbonline1111@...>
Sent: 15 May 2021 16:56
To: main@... <main@...>
Subject: Re: [JewishGen.org] Different date on birth record #romania #records #yizkorbooks
My maternal grandfather was born in what is now Belarus and did not know his birth date, just that it was during Passover, so his children "gave" him a birthday, April 15.
My father's birth certificate says he was born in NYC on March 30, 1917, but we always celebrated his birthday on March 29, because "my mother said that's the day I was born."
While the notion that that October 22 was the date of the bris and well might be the correct answer in this case, as my family history shows, there are many reasons that exact birth dates are not known.