Meghan Markle and Prince Harry are reportedly feeling anxious about a new German documentary that threatens to expose details of their past, potentially jeopardizing their carefully crafted American rebrand. The upcoming project, led by experienced royal documentarian Ulrike Grunewald, has the Sussexes worried as it could bring to light information they would prefer to keep private, according to sources.

Grunewald and her team have traveled to Montecito, California, where the couple resides, to interview members of their community in an attempt to uncover the truth. Former royal editor Richard Mineards, who now lives near the Sussexes, revealed in his column for Montecito Magazine that he was "grilled" for two hours by Los Angeles-based producer Melanie Hillmann under Grunewald's direction.

Despite the Sussexes having released several tell-all projects in the past, they had control over what was made public. "There are many things that both of them, especially Meghan, don't necessarily want in the public domain," an insider told OK! U.K.

While Prince Harry's party years were well-documented, Meghan Markle's personal life and details about her previous marriage to American film producer Trevor Engelson haven't received comparable attention. "It's no secret that they both led colorful lives before they met each other, and while Harry has spoken about a lot of mistakes in his book, there are still things about Meghan we don't know," the insider continued.

The source suggested that Meghan has "brushed over" certain details from her past, but there could be people from her inner circle "willing to speak out." Engelson, who was married to Meghan from 2011 to 2014, has not publicly discussed their split. However, the insider hinted that the producer could be a potential interview for Grunewald, stating, "Her first marriage didn't end well and her ex-husband is yet to speak out - but who knows, for the right amount of money, he may have his say."

As the unscripted series' release looms, the Sussexes are focusing on their Archwell initiatives. American royal commentator Kinsey Schofield recently noted the difference in the couple's approach to engagements during their trip to Nigeria. "I do think that Meghan is the skilled, trained actress, and Prince Harry has a bit of a problem hiding some of his anxiety sometimes," Schofield told GB News. "Meghan being by his side certainly calms him down and helps him out throughout that process."

Schofield also acknowledged that the couple's objective in Nigeria was likely to court the country for a future Invictus Games and that they "probably did a great job doing that." Their time in Nigeria brought positive attention to their foundation and what they've been focused on since leaving the royal fold. "This was great PR for them because if you just Google Meghan Markle today, 90 percent of the headlines are about how glamorous her wardrobe was, how beautiful she was," the podcaster explained.

However, the source claimed that the Sussexes are now "desperate" to leave everything behind and "start afresh," with Harry fearing that their "new happiness could be ruined if Meghan's past is investigated." The insider also suggested that the new documentary could shed light on the "fall-out with [Princess] Kate and dismiss the Sussex camp narrative that it was all Kate's fault."