The wedding is the wedding of brother and sister-in-law, which has little to do with your sister. The cost of the wedding should be borne by your brother and sister. Besides, most weddings are held in hotels. When holding a wedding in a hotel, you need to pay the venue fee, water table fee and wine fee, including wedding wine. If you have your own ideas, you can buy wedding wine for the young couple to celebrate their wedding. If you don't want to buy it, that's fine.