upsell item breakfast = Breakfast
upsell item items cats, dogs = petsPets.
2.) Insert these identifiers into the status fields for invoice items or upsell items
Settings > Properties > Upsell Items > Description: Your description|Your identifier
By adding the same identifier to multiple upsell items or invoice items you pool them into a group
3.) Create a custom report. Use the fields that you need and make sure to use the field 'Invoice Status Values'