I'm pretty vague on the time line NightMistBlue but Randy semi-retired after having health issues while performing with the World Class Rockers.
https://en.wikipedia.org/wiki/World_Classic_Rockers
A WCR show would only feature Randy for the first 15/20 minutes, during which he'd sing Take It Easy, Take It To The Limit and maybe one or two others, stick around for Hotel California then leave the stage.
Joe was saying publicly, probably during interviews while he was publicising Analog Man, that he wanted the Eagles to change their set list. He surprised everybody by announcing that he was spending the summer touring as special guest with somebody like Kenny Chesney. I think that instigated the History Of The Eagles show.
The dates with Chesney (I think) turned out to be short and sporadic, Joe returned the Eagles for some summer dates, continuing with the old set list but I think a commitment to change the set list was agreed.
The format, to tie in with the documentary. of a chronological trip through their career was suggested pretty early and the possible inclusion of former members. Bernie and Randy would need substantial time to get into shape and reach the standard required to perform at an Eagles show. Bernie did that, Randy didn't.
Henley's confirmation is from early July 2013;
There's no doubt that they were both approached to participate in the HOTE tour. I've not come across any evidence that they actually spoke to Randy directly."Bernie Leadon is definitely on this tour, Randy Meisner, if he were healthy and willing, might have been included, too, but his current health will not permit. We are all wishing him well."