When a mix and match discount is applied in retail server it only applies for the lines configured and only apply once. We would like to spread the discount on multiple cart lines.

Business offer: "Buy a mobile subscription and you get $50 to buy mobile accessories for"

To accomplish the above scenario we would configure a M&M rule with the following lines
Line 1: Category = "mobile subscriptions", number of products needed = 1, line group = A
Line 2: Category = "mobile phone accessories", number of products needed = 1, line group = B

We set the discount amount = $50, on M&M header.

Now, let's go to POS and add some products:
Cart line 1: Mobile Phone A, price $0, M&M discount rule applied, discount $0 as price is $0
Cart line 2: Mobile Accessory A, price $35, M&M discount rule applied, discount $35 as price is $35
Cart line 3: Mobile Accessory B, price $15, M&M discount rule NOT applied, discount $0

The issues i Cart line 3. Even thought we have a discount amount = $50 on the M&M header all that value will not be utilized as the discount is not spread on all cart lines containing products valid / in scope.

It would be great if this was possible, to configure if the discount should be spread across products candidates.

I see a lot of businesses having these kind of offers. Either they are not using D365, or they are using a customization, or they are using manual discounts.