I believe that Carole Stevens, manager of Blackmore's Night, is Candice Night's mother. If so, the possibilities for codependency shoot sparks like a catherine wheel.
Also, I think the DP band agreement is such that four voting members must say yea or nay on a fifth member joining, even for a one-off gig. It seems extremely unlikely that Paice, Glover, and especially Gillan would vote Blackmore back in even for a few gigs. For a good illustration of why, see the "Come Hell or High Water" video. Also, DP without Blackmore is quite successful and, most important, happy with Steve Morse. I doubt they'd want to slight him.
It would be more likely that Blackmore would reform Rainbow, maybe even with some Blackmore's Night players, and get his rock-and-roll ya-ya's out that way.