It is difficult to find much or make head-way with this.
I am unsure if this is the same family, but I will post in case it provides any leads
From Gentlemans Magazine Jan 1847:
Marriage of Charles Brown STUART to Charlotte Agnes CLAY
16 July 1846 Allahabad
At Allahabad, Charles Brown Stuart, esq. 3rd Native Infantry, son of the late Col. James Lewis Stuart, Bengal Army, to Charlotte Agnes Clay, second daughter of Capt. Knightley Musgrave Clay, of Laches, in France.
Same information with slightly different name for wife:
Bombay Times and Journal of Commerce (19 Aug 1846) gives the wife’s name as Charlotte Agnes Musgrave CLARY, daughter of Knightly Musgrave Clary Esq of Loches in France