Mini page when saving record in object

Hi,

We have a object for Sets in our Main Application. We are thinking of having a Mini page when we are saving a new record in our set object. So when a user adds a new entry to our Sets record page then when he is going to save it, there should be a pop-up to decide which entries they want to add and then when he selects them, then all data should be added to the record. How should I do this? I can make a process for adding a mini page?