DB Design for Memberships

[t2tt]

I need help designing a separate lookup database that allows me to find information about members quickly. On our main system each account can have 3 sub-members linked to it including the main which makes 4. They can only purchase an event once per member + sub member. Each member has its own 15 Digit ID.

I need help figuring out how to join Members and Events so i can easily lookup e.g 'Event Name' and It will return all the accounts & sub account(s) which have not purchased anything And possibly by 'Membership Number / Surname' etc.. We also must be able to see which main account id it is linked too on the results

MemberID  (15 Digit Char) 
  Mem1 (Main Acc) (ID, Fname/Lname) 
  SubMem2 (ID, Fname/Lname)
  SubMem3 (ID, Fname/Lname)
  SubMem4 (ID, Fname/Lname)

EventID
  EventName (Which Event?)
  Purchased (Has Acc had a purchase for said event?)
  Members Available (Which members are still able to purchase for said event? [Needs Main MemID + First/Last Name of  SubACC)