Thank you sancti....my understanding is that the OPR Marriage records have basic information on them. That it is after the 1855 Scotland Registrations; with the wealth of information.
My own great great grandparents' 1847 Glasgow Marriage for example have their names and
that is pretty much it. No mention of their parents either.
As I have previously mentioned, on my great great grandfather Valentine Armstrong's Death
Registration 1859 September 1, Glasgow, Elizabeth Houston identifies her self as his half sister and gives (their mother) as Isabella Joyce. So rather than supposition, there are several other Scottish documents with John Houston/Isabella Joyce as her parents