If you already know the description or Unique Name of the datum element you want to add to the group you can use this method:

Press the button in the Members tab toolbar. The following dialog is displayed:

Type in the Unique Name or Description of the element you want to add in the Name textbox. This is a mandatory field.

While you type, any elements matching the typed text is displayed in a dropdown:

Select the element you want to add. Note that the From and To values will be populated, but will only be enabled if the Group Type the Group you are trying to add to, accepts partial elements i.e. the Partial switch is set to “Yes” in the Group Types form.

The membership start date will default to today's date. You can change this date but note that you can only select a membership date between today's date and the Group's start date.

Pressing the Add button will add the element to the Group as a member.