Subgroups are useful when you want to use just a subset of data from a Main Group. They will stay in sync, but allow you to use Rules and filters to pick which items to include in the subset.
How to Create a Subgroup
In order to create a Subgroup you must have first created a Main Group (also called simply "Groups"). You need to do this first, because a Subgroup is only a subset of a Main Group and therefore cannot exist without them.
Once you have a Main Group, simply begin creating a new Group as you normally would. You will be presented with a number of options for creating the new Group, but the one you want to use is "Segment an Existing Group.". Click this box and more options will appear.
You'll need to first select which Group to segment. Use the drop-down to view all of your Groups and choose the appropriate one. Next, enter a name for the new subset. It may be helpful to you to include the name of the Main Group in the name of the new Subgroup. For example, "Birthday Party Guests - Kids" clearly indicates that the Main Group is "Birthday Party Guests", while the Subgroup contains just "Kids."
So now you have your Subgroup created. But it's basically just a copy of the Main Group at this point. How do you turn the a Subgroup into a subset of the Main Group? Easy, you use Rules.
First, navigate to the People tab of the Subgroup. If you have just created the subset, you should be there already. You'll notice that a new button has appeared in the upper right-hand corner of the screen labeled "Rules." Click on this button to bring up a side menu.
On the Rules side menu, you can press the "New Rule Set" button to add a new group of Rules. Rules can be grouped together in rule sets so that you can create conditions for a Rule to be applied. For example, you may want to create a Rule to include only people that are "Kids" and live in the neighborhood "Fairfax." By using a Rule Set, only people that meet both these conditions will be added to the Subgroup.
Adding a specific Rule is easy. First select the Field you will use for the Rule. This can be any Field from the Group. Next select the criteria for the Rule. This can be that the Field "contains", "does not contain", "equals", etc. a specific value. You will enter this value in the "Value" field.
So, for example, the Rule "Type", "Equals", and "Kid" will filter for items in the Main Group where the "Type" Field is exactly equal to "Kid."
To delete any Rule, simply click the trash can icon next to the Rule. After you have created your Rules and Rule Sets, press "Apply Rules" at the bottom of the side menu to apply the Rules to the Subgroup. You will immediately see the list update to display only the items that meet the criteria you have just created.
Subgroups pull all of their data from the Main Group. Therefore, if you would like to add a new Field to a Subgroup, you will need to add the field to the Main Group. It will then appear in all Subgroups associated with that Main Group.
However, you can edit People data from within a Subgroup. Any changes made to an Person will affect the Main Group and all associated Subgroups. This is because an individual Person is treated as the same data point between the Main Group and all Subgroups. This means you have to be careful! When you edit details for a Person within a Subgroup, it may change data in many other Groups.