Reading through the autobiography of Gaspard Weiss today I rediscovered something intriguing that I had read once before.
"Les enfants Baumgarten avaient hérite d'un oncle chacun environ £1500, soit 36000 francs. Cette ennuyeuse affaire, si importante pour les hommes de droit qui me réclamèrent 51 Guinées, retarda notre mariage jusqu'au mois d'août; de plus, par contrat, nous nous engagions, au cas où je retournerais dans mon pays, de placer ce capital en Angleterre au nom de mes enfants. M. Baumgarten vit au bout de quelque temps que cette clause était injuste et il fit tout ce qu'il put pour la faire modifier, afin que cet argent nous fût rendu." Weiss (2012).
Roughly translated, it says that each of the children of Samuel and Mary Baumgarten (née Joynes) inherited £1500 after one of their uncles died, and it was right before Gaspard Weiss and Marie Baumgarten were married in 1775. I'm pretty sure £1500 was a large amount then (the National Archives UK's currency calculator puts it at a value of £95500 in 2005's money), and considering at least four of them made it to adulthood (out of eleven children in total) that's a substantial amount of money to be passing on at the uncle's death.
On the paternal side I only know the date of death of one of Samuel Baumgarten's brothers - John Henry, who died in 1770. Having read his will, he left all his money to his siblings and not to nieces and nephews. I don't know of the wealth of any of Samuel's other brothers nor when they died. I do, however, suspect that the uncle in question lived in England, of which none of Samuel's other brothers did.
Of Mary Joynes' brothers, Bartholomew, Samuel, Thomas and Henry, I assume Bartholomew and Henry died young (likely in childhood) as they weren't mentioned in their father Henry Joynes' will - written in 1754, Thomas died at age 28 (1750), when he probably wouldn't have had time to amass a large fortune, but Samuel was a prominent lawyer who worked in the Middle Temple and had a number of high profile and/or high society clients. He certainly could have left a fortune of the magnitude left to the Baumgarten children. According to his will, Samuel Joynes, after divvying up most of his belongings amongst friends and family, left the remainder in equal shares to his sister's children - Mary and Samuel Baumgarten's children.
Samuel Joynes died on June 10, 1770, which fits with the uncle in question dying before 1775 when Marie Baumgarten and Gaspard Weiss married. So I don't know for certain, but I believe it was Samuel Joynes who left £1500 to Marie Baumgarten.