](I wonder where the ladies of the party disappeared to during the Gardiners' morning visit to Pemberley, or were the Bingley sisters the only women in the group?).

I think in chapter 3 we know that Bingley has five sisters:

..."that instead of twelve he had brought only six with him from London -- his five sisters and a cousin. And when the party entered the assembly room it..."

so I think if all the sisters are invited and if there are a married ones like Mrs. Hurst who brought their husbands with them , and may be their elder children, and Bingleys cousin who is mentioned above with probably his wife , this for sure be a large party of men and women!