If you search "Princess Diaries 12" on Reddit or Tumblr, the demands are passionate and specific. Here is the fan-made manifesto for the next book:
The plot delves into rumors of a "suspected royal affair" and a showdown with Grandmère over her own nuptial plans. A Return to Beloved Characters princess diaries 12
Mia's husband, Michael Moscovitz, is forced to self-isolate after potential exposure to the virus, leaving Mia to deal with her demanding royal grandmother alone. If you search "Princess Diaries 12" on Reddit