Android SQLite - How to represent groups within a table?

Let me start by giving a context.

I have 2 tables joined together by a many to many relationship as shown below.

In my Android application I have a need to show a list of the contents in the "JoinTable" (The join table will be filtered depending on the Table1 ID, this is the content that will be displayed to the user.)

Problem: I want the user to be able to group certain rows of the JoinTable together. I need to model this grouping system in the database so it can be queried later and the groups reappear. What is the best way to design the database with this capability?

Some more detail from a user perspective: When a user selects an item from table one, that ID is sent to the next activity. The next activity queries the join table for the appropriate content. The way it's working now, it just shows one item per row from the JoinTable. The user should be able to for example, drag an item onto another item to group them together.