I think lady catherine wanted her daughter to marry mr darcy because of two possibilities
One : being she was worried for her daughter's future in this era and wanted her nephew to look after sickly anne de bourgh should lady catherine pass away
Two: when you consider how full of herself lady catherine is she may have thought that she could control darcy ( and with him, his estate pemberley ) through the marriage of her daughter and her nephew.
I mean, we have seen how much she likes control others or "be of use".
Lady de Bourgh wants her daughter, Anne, to marry Darcy because she believes it would secure her daughter's social standing and financial stability. Additionally, Lady de Bourgh views Darcy as a suitable match in terms of social status and wealth, and she values such considerations highly in choosing a spouse for her daughter.
She wants her daughter to have a high social standing in society
Lady Catherine lied to Elizabeth by saying that Mr. Darcy had agreed to marry her daughter, Anne de Bourgh. In reality, Mr. Darcy had not proposed to Anne and had no intention of doing so. Lady Catherine's intention was to discourage Elizabeth from pursuing a relationship with Mr. Darcy.
Miss de Bourgh
Lady Catherine de Bourgh, Mr. Darcy's aunt, was most displeased by his marriage to Elizabeth Bennet. Lady Catherine had expected Mr. Darcy to marry her own daughter, Anne de Bourgh, and was not happy that he chose Elizabeth instead.
Lady Catherine has already arranged for Darcy to marry her daughter, Anne de Bourgh, believing it is the perfect match for enhancing her family's social standing and wealth. She is determined to see this plan through, regardless of Darcy's own feelings or desires.
Lady Catherine is Fitzwilliam Darcy's aunt
Yes, Mr. Darcy is the nephew of Lady Catherine de Bourgh in Jane Austen's novel "Pride and Prejudice". As Lady Catherine's nephew, he stands to inherit her estate of Rosings Park.
Lady Catherine de Bourgh is Mr. Darcy's aunt in Jane Austen's novel "Pride and Prejudice." Lady Catherine holds a position of power and influence in society and plays a significant role in attempting to control the romantic pursuits of her nephew, Mr. Darcy.
Lady Catherine demands that Elizabeth refuse Mr. Darcy's proposal of marriage and promise to never enter into an engagement with him. She also commands Elizabeth to pledge not to entertain any thoughts of marrying Mr. Darcy in the future, asserting that he is intended for her own daughter, Anne.
The teacher associated with Lady Catherine De Bourgh is not hers, but her daughter, Anne's. This is Mrs. Jenkinson.
Miss De Bourgh is a character from Jane Austen's novel "Pride and Prejudice." She is the sickly and overly sheltered cousin of Mr. Darcy, and is portrayed as a rather timid and reserved character who is dominated by her mother, Lady Catherine de Bourgh.
Lady Catherine told Elizabeth that she disapproved of her engagement to Mr. Darcy and insisted that she break it off. She also made it clear that she expected Elizabeth to obey her and marry a more suitable match of her choosing.
If you are speaking of Pride and Prejudice, I am pretty sure it is Lady Catherine de Bourgh's daughter.