On Maria Pavlovna (the elder) --
Maria Pavlovna was born a Princess of Mecklenburg-Schwerin, an ancient and important German mediatised family. The problem with the Mecklenburgs is that their fortune and their influence had been divided over the years by the rise of cadet branches (Mecklenburg-Schwerin, Mecklenburg-Strelitz, etc.). Maria Pavlovna was raised to believe she should be a Queen regnant, but this was not to be.
Maria Pavlovna arrived in Russia as one of the most important women at court; Maria Alexandrovna (daughter of ALexander II) had served as official hostess due to her mother's long illness, and had left Russia to marry the Duke of Edinburgh. As a result, Maria Pavlovna was the number three woman at court after the Empress, and the Tsarevna (Maria Feodorovna).
As time went on, Maria Pavlovna was bumped out of the highest positions by the majorite of Grand Duchesses Olga and Xenia. Grand Duchess Elizabeth married into the family and was universally regarded as the most beautiful and interesting of the foreign Grand Duchesses. When Alexandra married nicholas and churned out four ravishing Grand Duchesses of her own, Maria saw her position as irrevocably eroded.
As Alexandra withdrew after 1905, Maria Pavlovna became bolder, asserting her primacy as the wife of the third in line to the throne. From the Vladimir Palace in Petersburg, and her palace at Ropsha, Maria Pavlovna effectivley set up an alternate Imperial Court; she entertained lavishly and frequently, she travelled extensively, and her influence was widely felt.
After the forced exile of her oldest son after his marriage to Victoria Melita and the death of her husband, she felt her power slipping, and it was then that she began to lash out at Nicholas and Alexandra with comments regarding the "annihilation" of the EMpress. She was quite desperate at the end.
Sadly, what Maria Pavlovna wanted more than anything came to pass; her son Kirill became heir, but by then it was too late.
She was, as was mentioned earlier, one of Cartier's greatest clients, commissioning hundreds of pieces over the years. When she died, I heard from a Cartier expert that she owed more than 250,000 roubles in unpaid bills to the Parisian jeweler.
Best,
Nick