Whom does Pip’s sister invite to Christmas dinner? How do these guests treat Pip?

You can find the answer to this question in chapter four of the novel. Because it was Christmas Day, Mrs. Joe invites several members of the local community to dinner, namely: Uncle Pumblechook, who was Joe's uncle, a cornchandler; Mr. and Mrs. Hubble, the local wheelwright and his wife; and Mr. Wopsle, the clerk from the local church. Prior to the dinner, Joe and Pip attend church, but Mrs. Joe, being too busy with preparations to accompany them, goes only "vicariously" through their attendance.
Pip opens the door to the visitors as if this were the general habit of the household; although, the suggestion is that it was quite unusual. Uncle Pumblechook brings two bottles of wine to the dinner, calling Mrs. Joe "Mum" respectfully. However, Pip himself feels "in a false position" among the visitors, for various reasons: he is not allowed to speak; the table is too closely cramped; but, most of all, "they wouldn't leave me alone." Pip is continually pricked with "moral goads" from the visitors, who prevail upon Pip to "be grateful" and state that the young are "naterally wicious." Joe, who also clearly feels rather uncomfortable, attempts to console Pip by spooning gravy into his plate every time the conversation turns to the natural wickedness of children.