@kylemabaso i'd go for a single user table to contain authentication details eg username, password, email address etc.
if you also have an optional membership number you should also add that to users.
With respect to certain user credentials, eg membership, then this will lead to you defining middleware based on this field so certain routes can only be accessible if they have a valid membership number.
what you should do next is to define your models and then work out the relationships between the,.
eg
- User (table = users)
- Lead (table = leads)
- Benefit (table = benefits) etc
if you are using separate tables for Employee, Volunteer etc then these will be a hasOne relationship to the user and then you can have a volunteer_id, employee_id field on the User model to map to these tables.
As its early days in your project, the best bet is to build up some models and migrations and then see what it looks like.
You may find using Laravel blueprint is helpful at this point, as that allows all your models, controllers and relationships to be written in a config file that you can quickly use to scaffold your app.