To clarify; I am thinking of him having 5-7000 so far, from his mother's side, which would be his primary source of income for living as his wage as a colonel is mostly eaten by required expenses. It would be what, 300ish pounds a year? It is ample for his comfort as a single man but certainly not enough to marry on and maintain anything like his present standards. (It is all relative, isn't it?! 300pa would be huge to most people then, but very modest, I think, for the son of an earl.) I plan for him to have a future inheritance of another 10k(?), secured to him via his mother's settlements - but Col. Fitzwilliam will get it only on his father's death. And yes, the earl's estate is sufficiently tied up that while there might be some minor other bequest, there will be nothing more substantial.

However, Lady Catherine and Lady Anne both had much larger fortunes than their sister-in-law, and in both cases, it was arranged to go to their younger children. Hence, Georgiana's 30,000. But as Lady Catherine did not have any younger children, her fortune is hers to dispose of however she wishes. It is, however, generosity with strings attached; she expects Anne to soon marry Darcy and be relocated to Pemberley and therefore, she wants to secure a new niece (and potential great-nephews and nieces), to be settled close to Rosings for Lady Catherine's pleasure. (Needless to say, things will not work out quite how Lady Catherine plans). Rosings is Lady Catherine's for her lifetime but secured to the de Bourgh line; going by the description of Lady Catherine being the one to grant Mr Collins the living of Hunsford, it isn't being held in trust or owned by Anne, it is Lady Catherine's.

I think all of that would be reasonable in Regency times - I am just checking to see if there is something I have missed.

I was thinking that Rosings must have an income of something like 8k a year, but I haven't found anything arguing a figure. I was pegging Darcy's total income at between 10 and 15k a year, most of it from Pemberley but some from investments and a couple of small estates that bring in 5-600 a year each.