Never did get any further with this.
Thomas parents names were a John Campbell and Francis Forrester, from his death cert, Elizabeth parents David Campbell and Janet Chalmers. I never did find Thomas birth or Marriage certs, but was able to find his parents marriage cert in 1800, you could be right about a 2nd marriage for Thomas but never seen it on his death cert, I'm wondering if this was the correct Thomas in the 1861 census with his father and possibly a 2nd marriage for him.