I will create a referral system for WordPress.It will be done. but I want when “Member A” invite others to join (ex. “Member B”) by using the ?referralId=MemberA query string, when Member B first time buy any product that time Member A get some cashback value(It will be set cashback value ex. 250) in our wallet. and when Member B invite Member C, then Member B get cashback value. Is there any WordPress plugin that can do that OR please help me for these stuck?