As to the ownership, I guess you can look at it as you own it, everyone owns it, no one owns it, that is more or less how I see it, all three in a strange state of limbo. I possess it and I can do whatever I want with it, however if you figured it out (and can prove it, not just I heard once from great uncle bobs step-son that I met once 25 years ago) then anyone else can too so everyone is on the same field, you just pieced it together first (or did you?). Yet this information is just that, who owns the fact that 2+2=4, no one.
Though there is responsiblity with this knowledge that we build up and keep. I for the most part am very transparent with what I find, I embrace it. We previously thought my GGG Grandparents were distant cousins, not so, first cousins and I made sure anyone who thought otherwise knew the truth (as icky as it may be). We are very open about our pasts in my family, my grandfather stole 2 boats when he was in his teens in the thirties, thrown in Juvinile Detention for theft over $10k. Yet these are all facts and we either have documentation to back our discovery or we have the person to tell us.
Yet there are 2 things that I know parts of the information for yet I am responsible for it as well. There is a child that was adopted, he doesn't know so saying things to other people about it is unfair to him and his family - maybe later in life he will be told, or maybe not, but that is not our choice to make for him or his parents. Also there is rumor that one of my cousins has half-siblings. Long story shot their father apparently got married over seas during WW2, never getting divorced, technically making all the children of his that we know here bastards.
The first example as I said it isn't my place to say anything, and I have it documented but stashed away from everything I make accessable to my family (My work book is all online). The 2nd one I would divulge to the proper people, however I would need to be able to prove it (Marriage certificate), even then I would have to be tactful about telling those people simply because of the implications.
So the short of it is everyone has a right to know as long as it is in proof and evidence. Is it your right to tell them, or someone else right? Would it damage the family integrity, they may still need to know but with tact and at the right time (maybe introducing this person to them at the same time?)?
