Filter By Sibling Category (Products That Belong To Cat1 And Cat2)

Dear Community Experts,

I am looking for advice how to setup CS-Cart Multi-Vendor to deliver the following 3 user-stories to my customer without major modification of how application works:

  1. As a Amateur shopper, in order to select good French wine that fits my budget, I want to see "Wines on sale" first, and then be able to narrow down the search to Red wines, and then apply filter by price range and country of origin.

    User journey: ON SALE -> RED WINES -> filter by Country + Price range

    Development challenge: "ON SALE" is not a standard category, but a special view (products.all.on_sale view) provided by "Bestsellers & On-Sale Products" addon. "RED WINES" is a classic Category. How to display categories on the products.all.on_sale view? Moreover, how to make a filter by price range on that page, as filter works there only via "Filter for homepage block" that does not have filter by price.

    Do you know a solution for this case, other then duplicate "Red wines" as a Feature, and implementing custom filter by price for that case?
  2. As Loyal customer, in order to find new wine I did not try yet, I want first to see what wines are coming in South America, then narrow down selection to wines from Chile, and then select among wines from specific category, e.g. Red wines

    User journey: SHOP BY COUNTRY -> SOUTH AMERICA -> CHILE -> RED WINES

    Development challenge: "SHOP BY COUNTRY -> SOUTH AMERICA -> CHILE" are category tree. "RED WINES" is a classic Category too. So each Wine belongs to 2 categories: from the Types subtree (Red, White, Dessert, Sparkling) and from the Region subtree (Continent -> Country -> Region). When user selects SOUTH AMERICA, we have to display its subtree (Argentina, Brazilia, Chile) and also all secondary categories that product have (Red, White).

    Do you know a solution for that, other then duplicating Types and Regions also as Features while having them already as Categories?
  3. As a Professional buyer, in order to extend wine card of my bar, I want to see the list of all vendors that produce red wines.

    User journey: ALL VENDORS -> RED WINE VENDORS

    Development challenge: Is there a block that would allow to list vendors that have at least 1 product in selected category?

    Do you know a solution for that?

Thank you all for contribution.