Free Domain only with other product

Hello again ??

I need to achieve the following situation in conjunction with WooCommerce Subscriptions:

I have a few subscription-products of the category “hosting”, all of which include a free DE-Domain. All Domains (incl. DE, COM, NET etc.) need to be sold as yearly subscriptions, but for hosting-products my clients wil get a free DE-Domain and at the same time they can choose between yearly and monthly subscriptions. for the hosting product.

So I have configured a coupon with a free product “DE-Domain” and tied it with the hosting-product, which is working nice on the first sight (I have placed the shortcode for the DE-Domain in the product-description of each hosting-product).

But in checkout, the coupon-amount is not applied to the DE-Domain only, but will be “shared” with the hosting-product, even if it’s on a monthly basis.

Example cart of the required set-up:

Hosting-Product “Basic” 40 € per month
Domain-Product “DE-Domain” 10 € per year
Coupon 10 € applied to all products of the category “hosting” & free product “DE-Domain”.
= “Basic” should be billed 40 € per month & “DE-Domain” should be free each year

But with the previously mentioned config, this is what happens:
= “Basic” will be billed 35,70 € monthly instead of 40,00 and “DE-Domain” will be billed 5,70 € instead of 0,00.

So instead of fiddling with the coupon stuff, I wonder if it would be possible to enable us to “connect” multiple domain-products with one TLD, e.g.

DE-Domain = 10 €/year
DE-Domain Free = 0 €/year

which would allow me to achieve the required set-up.

I’m aware that this requirement may be a bit special, and I have tried to achieve it by testing several plugins related to Coupons, Bundles, Chained Products etc. but none of them is working as required.

Is there any chance that you can help me with this?

Sorry for my low english skills and looking forward to hearing from you.

Thank you in advance and kind regards,
Sascha