Thanks for previous feedback.
While looking for another sibling I happened upon a birth 1 Mar 1849 in Petty of a child Jean with father Donald. The document does not list a mother. Donald 1821's mother was Jean so thought that was a possible clue this could be a child in my tree.
The birth (see attached) noted in "something" of Petty.
The 1851 Census has a Donald and Jane with daughter Jean and a son Hugh Walter Clark born about May 1850 in Petty. However, that Donald is listed as born Cawdor, Nairn. I have Donald born Petty 14 Dec 1821 and baptized 19 Dec 1821. The Jane on 1851 census is born Ardersier which fits the marriage documents. The 1861 census lists same birth location for that Donald
Would there be any reason for Cawdor, Nairn being listed as birth location? A search of Scotland's People does not find a birth for a Donald Clark around 1821 nor does FamilySearch.