After you create a list, regardless of the method or criteria used to populate the group, you can manually add individual members, even members not satisfying your original criteria.
From a research list, in the Members list, click Add member. The Add research list member screen appears.
Click the search icon to access the Individual Search screen. From here you can search for and select the new member. You can also add constitutes to your database from the search screen by clicking the Add button.
Once the new member has been selected or added, from the Add research list member screen, click Save. The new member is added to the list.