Adding multiple data entries to one polygon

Adding multiple data entries to one polygon

Hello, I'm try to list a number of activities and groups that use a particular community centre.  I've created the relevant layer and a polygon that matches the building.  I've entered the first activity using the building but cannot enter another.  Can anyone advise on the best way to do this?  The only way I can think of is to list each activity as a single point within the building footprint.