For such a request you can look at assigning a dependency to products. For example, as per the IT Shop guide, when a printer is requested, a flat-rate installation charge has to be requested at the same time and toner might be requested optionally. A product dependency could be used in this case.
Please refer to the guide here: Defining Dependencies between Products
This means that you can enforce the requirement for one product when another is requested, and notify the user to such.