Hi,
I'm the webmaster of the Osborne Origins website. Most of the Osborns I've collected information on and posted at the Osborne Origins website are unrelated to me, this line is in fact my own. And I'm the very guy who many years ago decided that Richard Osburn's father is Benjamin Osborn b. 26 Jun 1726 in Baltimore Co., MD. Sorry I didn't see your post sooner.
Anyway, there is absolutely no direct evidence that they are father and son. They are definitely related and there is a strong, but long, circumstantial case. I would not worry that none of the *known* sons of Richard Osburn are named Benjamin.
I suggest that you start by looking at my family group record for Richard Osburn at Osborne Origins --
http://www.osborne-origins.org/linkrecs/f1.htmThen follow the link for Richard's father to get to Benjamin Osborn's family group record. There are notes and discussion on each of those family group record's.
Still, the story is longer than what is on those family group records. I would be glad to talk to you in person. If you email me, perhaps we can arrange a phone conversation. You could explain what you already knew about Richard and I could explain how I got to Benjamin as his father.
By-the-way, I descend from Richard through both his son Doctor Frank and his son Bartholomew.
Lee Osborne
lee@osborne-origins.org