Calculate revenue percentages based upon broad product categories and nested product vendors

I am running into an issue when trying to determine revenue percentages in regards to certain products we offer. For clarity, we are an exterior remodeling company. We sell products like windows, doors, siding, etc. I have created a pretty basic report. I would like to determine:

1. What % of revenue is tied to each product
2. What % of revenue is tied to each vendor's share of that product's revenue.

For example, say we have a total revenue of $10. Windows account for $8, doors account for $2. The first % column formula would show that windows have 80% of the revenue, doors have 20% of the revenue. Pretty straight-forward. This would satisfy my requirements for #1 listed above. Next, let's delve into the windows. We sell from multiple window vendors. Let's say we sell $4 of Andersen, $2 from Milgard, and $2 from Alside. My #2 % column formula show that Andersen account for 50% of window revenue, Milgard accounts for 25% of window revenue, and Alside account for 25% of window revenue.