Adding Members to a Limited Liability Company (LLC) you will want to create a Unit Class in the LLC that you are working in. When it is percentage based you will want to set the authorized amount of the percentage class to 100.
Once that data has been entered in you can go to Securities and issue a percentage to those stakeholders.
There is a tab in the Securities section to see all the Members (current or historical).
Additionally, after all the members have been listed they will now show on the Overview of that entity in Athennian.