In the upper echelon, sometimes, profit wasn't the most important thing but affiliation. The Quinns and the Blacs particularly held their affiliations with the highest importance, and deep in Cosette's heart, even though she disapproved of all these people's presence, her grandparents invited them all for her.
Since the elders of each family weren't getting older and the newer generation was already at the age of understanding what affiliation was, now was the time to let the younger ones continue these ties. Cosette already told herself she was still lucky, because her elders didn't immediately set her up in a marriage but instead introduced her to their guests and told her to get to know the young masters of the Quinn and the Stone family.
Cosette probably had to thank Conrad for that, knowing her father would've guessed her grandparent's scheme.