Normandygirl
I must be reading the OP differently from others on here. The OP hasn't stated that she wants to reunite with anyone, only that she's sad that half of her grandson's family history is missing. She wants to make sure that, should there come a time when they, or their children, or their children's children want to know the complete family history, the missing half has been documented. There is nothing wrong with that.
I suggested she writes the stores down and leaves them with her solicitor but that is what the OP wants to do.
As *Violetsky says: Plus there are far less public channels to at least try
A blog is different.
Blog:
noun
a regularly updated website or web page, typically one run by an individual or small group, that is written in an informal or conversational style.
verb
add new material to or regularly update a blog.
"it's about a week since I last blogged"
