Example:

Checkout

↓

Upsell 1

├─ Accept → Upsell 2

└─ Decline → Downsell 1

Downsell 1

├─ Accept → Upsell 2

└─ Decline → Custom Page / Dashboard / Upsell 2

Upsell 2

├─ Accept → Upsell 3

└─ Decline → Downsell 2

Downsell 2

├─ Accept → Upsell 3

└─ Decline → Custom Page / Dashboard / Upsell 3

This repeats for however many upsells/downsells we want to have in our funnel.

Thank you