Fatfreecrm Fat Free CRM → 0.9.10 "Alekhine"

I have this issue upon entering data for a large accounting firm whose clients are Groups of companies. What kind of mechanism would I need to relate companies within a group and then branches within a company?

Essentially setting up a hierarchy:

Group 1
  |
  ---- Company A
  |       |
  |       --------- Branch A1
  |       --------- Branch A2
  |       --------- Branch A3
  |       --------- Branch A4
  |
  ---- Company B
  |       |
  |       --------- Branch B1
  |       --------- Branch B2
  |
  ---- Company C
  ---- Company D
  |       |
  |       --------- Branch D1
  |       --------- Branch D2
  |       --------- Branch D3
  |
  ---- Company E