Good Wednesday morning Mike. More often than not I will copy/paste the information into a text document. Repurpose the information and then re-post.

You just go back to the blog post and edit it.  Then, scroll down to groups and check the appropriate one.

that being said, I don't really see the point. If it's old, no one will see it and it will essentially be in the archives for the group.

First, why would you want to?

Second, do what Debbie Gartner suggested if you just want it in the group

Third, if you want it at the top of the list in a group, then use the old blog post to write a new one and then check the box while posting it.

Just go back to the older post and edit it and add it to the group you want it to be in.

It has been stated that the groups have lost their luster and are no longer relevant.  That will be changing so for now, forget it.