If Elizabeth is returning to the Pemberly area after a long absence, then why hasn't she though of Jane? If Miss Bingley and Mr. Bingley both cross her mind, then Jane probably would too. Nice takes on Mary and Mr. Bennett, though.
Was Mr. Bingley living in Netherfield at the time of Darcy's wedding? The last chapter mentions that he and Jane eventually move to a place not too far from Pemberly.
Are Kitty and her husband at the wedding? That would have to be pretty loaded.
Oh, was this their honeymoon? Now I think I'm starting to get it. I thought they'd taken a trip after being married for some years.
The summary for the fanfic says "Elizabeth and Darcy return to Pemberley to begin their new life together." The "to begin a new life together" part should strongly hint at that this is a case of the couple returning home after the honeymoon.
Also, she does think of Jane, regarding how her sister will feel to have their mother visiting so frequently.
The book says that the Bingleys remained at Netherfield for a year. While it does not say explicitly when the marriage(s) took place, it's suggested that they both take place at the same time or in close conjunction. I gathered from this that it was likely they would still be there when Elizabeth and Darcy returned from their honeymoon.
If you mean Lydia, it is suggested in the book that she and Wickham did not attend the wedding, as the book describes the letter she writes congratulating Lizzy on her marriage. Considering their relocation as well as the ill feeling between Wickham and Mr. Darcy, their wedding attendence seems unlikely.