The First and foremost step for adding a combo is to create the Menu items which you want to add in combo.
Go to eZee Burrp back office > go to Outlet tab > Menu item configuration > Menu item > New Menu item.
Add all the Menu items one by one like this which you want to add in combo list.
After adding all the items add One Menu item with a Combo Name. While making the Combo item: Go to Modifier group and Click on New Item and select “Set As Menu item” A list of all combo menu items which you have added from the Drop down list beside it. Select each item one by one and save it.
After adding all item one by one save the Combo item and restart the eZee Burrp
And check the result.