Thank you for your help. It does give the possibility that there is a connection with the Picot family.
I have looked further into the Jeanne Huelin who was the child of Jean and Marie Madelaine Dallain and have discounted her as my Jeanne.
From census records
In 1841: at Augerez, St Peter:
John and Rachel Huelin both age 40 (b abt 1801)
Philip 13 (1828), William 11 (1830), James 9 (1832), Jane 1 (1840)
And two older Jane Huelins one 68 (b abt 1773), the other 65 (b abt 1776).
In 1851:
John Huelin 51 (1800) Farmer Head b St P
Rachel 50 (1801) Wife b St O
James 19 (1832) son, Jane 11 (1840) b St P
Jane Huelin 78 (1773) widow mother b St O
Jane Huelin 74 (1777) unmarried aunt b St P
From Jerripedia
Baptisms at St Peter
Jean : 31 Aug 1823
Philippe: 13 Oct 1827
William: 07 Mar 1830
James: 25 Mar 1832
Jane: 13 Mar 1840
All children of Jean Huelin and Rachel Sauvage
Marriage at St Peter:
Jean Huelin of St P and Rachel Sauvage of St O
24 Nov 1822
Baptism at St Peter
Jean Huelin son of Jean Huelin and Jeanne Du Heaume
23 Feb 1800
Marriage at St Peter:
Jean Huelin of St P and Jeanne Du Heaume of St O
22 Feb 1799
So Jean senior (deceased by 1841) has a sister Jeanne b abt 1777. Assuming Jean to be similar age to his wife, the only brother and sister with these names and ages are the children of Jean Huelin and Marie Madelaine Dallain.
Maybe my Jeanne was never baptised