Hi Dano,
Did you check the IGI whether the entries were extracted or submitted?
I had a wee look in the BVR's and all the children you mention are listed as being born to Thomas REA and Janet THOMSON at Bothkennar. Daughter Mary born 8th November 1806, christened 15th November 1806, so all the children you got from SP match up. (Apart from slightly differing dates of birth - BVR's give births and christenings)
Alexis Thomson REA is the only child/daughter listed to Thomas REA and MARY THOMSON born 3rd September 1826, christened 17th September 1826 at Bothkennar
Here are the Marys which show up when entering the search criteria as "Mary Rae/Rea born 1810 +/- 5 years, Stirlingshire":
RAE, Mary born 1805, St. Ninian's, Fa: William RAE, Mo:Janet GILLESPIE
REA, Mary born 1806, Bothkennar, Fa: Thomas REA, Mo: Janet THOMSON
RAE, Mary christened 1812, Larbert, Fa: William RAE, Mo: Betsy TOWERS
RAE, Mary christened 1814, Larbert, Fa: Peter RAE, Mo: Jean BOYD
The above Mary (daughter of William Rae & Janet Gillespie at St. Ninian's) was born 25th September 1805 and christened 7th October 1805.
I know you've probably got all this stuff but as you say, sometimes a fresh pair of eyes or a slightly different perspective can make all the difference.
You'll know also that all you're likely to find are the couple's Banns in the OPR's rather than an actual marriage certificate as 1805/06 was well before Stat. Reg.
The best of luck trying to sort them out!
Anne