In order to add profiles to a project, they must first be listed on Geni. Therefore, if there are not yet any profiles for those individuals, you would be required to create profiles for them beforehand.
Once the profiles have been added on Geni, use the 'Actions' button to "Add to project". You will have the option to either create a new project or add the profile to another project you are either following/collaborating on. You may add any public profile that you have permission to edit. If you do not have permission to edit the profile, a request is sent to the profile manager to add the profile to the project.
Note: Only public profiles may be added to projects.