Common relative as a marriage witness?

[Lisa in California]

Mr. Tierney married Miss Flood in Dundee, Scotland in 1869.  He would have been about 31 years old, she would have been about 35.  (I have their full marriage details, thanks to RootsChatters.)  Their parents were deceased by 1869.  The witnesses to the marriage were Michael Clarke and Elizabeth Flood.  RootsChatters and I have researched Mr. Clarke and Ms. Flood, without finding solid proof of their relationship to the couple (Clarke was Tierney's mother's maiden name).

My question, please:  was there a common relative (uncle/aunt, brother/sister) who would have been asked to be a witness to a marriage, or did the bride and groom generally just ask a relative or friend who happened to be free that day?   

Again, we've extensively researched this couple, so I'm just wondering if it was common to ask a certain relative or friend.  Thank you, Lisa. 

[Elwyn Soutter]

In my experience there's no set arrangement. It can be a sister, brother, friend or whatever. All depends on the couples inclinations.

[Lisa in California]

Thank you, Elwyn.  I appreciate your reply.   

[Jebber]

In England, if you look through Parish Registers you will see the same person or people signing as witnesses,over and over again,  often it would be the Church Warden or Parish Clerk, I imagine something similar happened in Scotland.

[Lisa in California]

I know very little about Scottish records.  I have an English ancestor who was a church warden and he did sign a number of records.  Thank you, Jebber, that is something to keep in mind.