160 votesDev commented
Yes, Smart Offers allows you to include a discount on products that are upselled after the checkout process. I have tried it on my store and it works perfectly.
Hope this helps!Dev commented
I have setup 1-click upsell as mentioned in this blog - http://www.storeapps.org/how-to-create-1-click-upsells-in-woocommerce/ - using StoreApps 2 plugins : Smart Offers (http://www.storeapps.org/product/smart-offers) and Buy Now (http://www.storeapps.org/product/woocommerce-buy-now/)
Works perfectly for me and sales have trippled after I started using them.