Promotion App or Sales Expansion App (or a feature))

we probably can have an app or add this logic as feature to one of the existing apps that is related to customers' sales. the idea is when an existing customers only buy a set of items and we want to to sell them another set of items too, we need to know what customers are buying what set of items, then, figuring out how to sell them another set too by bundling, grouping a set of items to promote them (this logic can stand alone as Promotion app or Sales Expansion app) and also can work with sales app that we have like rebate, restriction, and insights. or we can add this as a small feature to one of our existing app (I personally prefer to have a separate app for this purpose).