How would i make a reverse 2 Up

PHP
1

I have an affiliate script called “post affiliate pro 4” and was wondering if it has the feature where you can do a reverse 2 Up or is there a way i can add it

2

anyone?

3

person #1 signs up and person #2 joins under person#1 then person #2 gets person #3 to join under them and they get a commission and person #2 gets Person #4 to also sign up under them but person #1 gets the commission for person #4 signing up and person #2 gets nothing. and so on so forth