Trying to create a bundle and not doing well

I am trying to create an automatic 15% discount applied at checkout, when any 1 product from Vendor A, AND any 1 product from Vendor B are added to cart. Discount only applies to those 2 products.

Native Shopify obviously can’t do it. I’ve tested Bundler and I can’t simply select Vendor or Collection, I have to hand pick the products and hit a limit.

Does anyone have some direction for me, I’d be incredibly thankful :)