Modifier groups is ideal for situations where you need to give multiple modifier options for buyers to choose when purchasing an item. For example, if you're selling a shirt, letting buyers to choose sleeve type such as long-sleeve or short-sleeve can be two modifier options you can give. In this case, you create individual modifiers for long-sleeve and short-sleeve. Then put them into modifier group, 'sleeve-type' and add it to the selling item. A buyer will get to select preferred sleeve type.
1. Admin > Modifiers > Modifier Groups. Click on the 'New Modifier Group' button.
2. In the General tab, give a name to the modifier group, and select the 'Choose existing' button. On the right, you get a list of modifiers, click on the one that you want to add to this group, and then click on the 'Choose'button to complete.
3. Create your modifier group and click on the 'Put Online' to publish the changes.
Other optional tabs:
Settings tab: Use this tab to control the minimum & maximum quantity that can be added. And also, to control if more information on the Modifier is shown