Descendants of both Ellen Charleston and John Joseph Charlston have had their DNA analysed by ancestry.com and gedmatch.com which discovered a close match (4th cousin level) between the two family lines.
I believe that this DNA path must have been from John Charleston through his son John Joseph(or Sam) and daughter Ellen.
I believe that the person known as John Joseph Charleston by his USA family was known as Sam Charlston
by his birth family in India.
This belief is supported by the DNA results, letters and photographs handed down through his USA family which identify his brother Charles and sister Ellen in India.