I'm looking for a birth record of my gggf john campbell born 21 july 1826.
His birth date was obtained from his Master Mariners Certificate No 10334
issued Dundee 6 may 1826.
Are you sure? If he was born on 21 July 1826 he wasn't born when his Master Mariner's Certificate was issued, which seems unlikely. So which is the correct date?
Edit: now that this latest message has been merged with your older threads I can see (a) that the certificate was not issued in 1826 and (b) that you have already started half a dozen threads with exactly the same query. As
JAP told you 13 years ago, this is not a good idea because multiple threads lead to confusion and duplication of effort.
I think that the name of his daughter, Elizabeth Baxter Campbell, is good enough evidence that his mother's name could have been Elizabeth Baxter, so the marriage you found is likely to be correct. However the marriage record is very unlikely to tell you anything about their parents, being long before the start of civil registration.
You keep on mentioning the LDS IGI but are you aware (a) that it is an
***index*** and does not necessarily have access to the original documents (b) that it is not comprehensive and (c) that it contains some very curious bits of 'information' that cannot be verified from an original document. (Though I am relieved to see that they seem to have removed the family tree of the Norse gods, including dates of baptism, that used to feature there.)