Do long-term things, such as how much the group purchase is full, cash back coupons or send a small course of treatment, or send a beautiful small gift. You can also do activities in the store, introduce a sister introducer to send an eyebrow trim or something, or forward it to your store on the day of group purchase. You design your own content, let the guests copy and paste it with one click, then come to the store to show the forwarded information, and send a small eyebrow trimming course on the day of consumption. Of course, screenshots don't count.