Here is a description in words:
The first upsell is a normal upsell.
Whether they say yes or no, they see Test Upsell 2
Then the complicated part is whether they say yes or no to that.
Test Upsell 2 also has Test Downsell 2. They will only see Test Downsell 2 if they say no to Test Upsell 2.
Regardless of what happens there, everyone will see upsell 3