Reflecting on the fallout of the bombshell Diana tell-all with Martin Bashir in 1995, the royal commentator said a Harry and Meghan tell-all could have similar results.
"I think Harry would be foolhardy at this point to have a tell-all,” Marlene said, before alleging the couple are in enough “hot water” over the Finding Freedom book.
"I think they would be foolhardy, absolutely crazy because it would not help their situation and it would certainly not help their situation with the British tabloids.
"I think a full-out war would be declared on them and I don't think that should happen but that's the last thing they should be doing,” she added.
Marlene then suggested that if Harry has any intention of “reconciliation” with his family, he and Meghan will avoid getting involved with any kind of shock tell-all.
Despite the claim, the Sussexes have denied they are planning to star in their own reality TV show as part of their lucrative $200 million deal with the streaming giant.
That said, a Hollywood insider weighed in on the rumours while speaking to the National Enquirer, saying it only makes sense the couple have something big planned, given their hefty fee.
“Everybody loves elephants and inspirational stories. But let’s be honest, that’s never going to pull in big money,” the insider reportedly said, referring to Meghan’s Disney+ gig.
They continued: “But footage filmed by Meghan and Harry as they left ‘The Firm’? Now that’s a $200 million show!”