I've been researching Charles and Benigna Weiss' son Egmont and decided to plug "Weiss" into the India Births/Baptisms, Marriages, Deaths/Burials collections of FamilySearch. I was surprised to find a record for Adelaide Martha Weiss, aged 17, daughter of Charles Nicholas Weiss, marrying Patrick White, aged 32, son of Patrick White, in Bombay on 12 Oct 1846.
Huh? Adelaide Weiss, firstborn child of Charles Nicholas and Benigna Catherine Weiss, was married to James Sheldon, a Church Missionary Society missionary, and they had at least five children together. And so she was, and so they did, but in fact she was married to Patrick White first.
And that explains why I have never been able to find a marriage record for Adelaide and James - because Adelaide's surname was not Weiss but White when she married him.
The family story goes that the family was in India and when the children of Charles and Benigna Weiss were orphaned, after their parents died in quick succession in 1845, the boys stayed in India and went to military school, and the girls returned home to England. That their firstborn daughter Adelaide married Patrick White in India, only a year after the death of her remaining parent, her mother, suggests that Adelaide may not have returned to England, but in fact stayed in India.
Adelaide married at 17 to a man almost twice her age. Although this was probably more common then than it is today it is tempting to wonder if it was a marriage of convenience, in order to provide her siblings with some stability and security in India. I have not found any evidence of children being produced by the marriage. When Patrick died on 26 April 1853 (information from FIBIS and the Glasgow Herald of 20 May 1853) at age 39 Adelaide was only 23. Adelaide's sister Caroline was definitely in India during this time - she married Henry Richard Hughes in Bombay in 1851. Her brother Frederick was definitely in India from 1850 until September 1853 when he returned to England - I have copies of some of his own notes which state this.
Perhaps after her husband Patrick died Adelaide did go back to England for a time, but she turned up again in Bombay, India, on 9 July 1861, marrying her second husband James Sheldon, who was a CMS missionary in Karachi. James and Adelaide were the same age, and I find it easier to imagine that they married for love rather than convenience.