Subscription Product Add-Ons

We sell various services with different add-ons for each product. Currently, we use Gravity Forms product add-ons for the add-ons. Recently we started selling add-ons/products that are subscription based, and we have been manually handling the subscriptions. This is getting quite unwieldy as one might imagine and we would like to automate this as much as possible say using WooCommerce Subscriptions.

A scenario:
We have a service that has various add-ons. Some add-ons are truly add-ons/variations such as Rush Processing or a service that is only applicable if that product is purchased. Other “add-ons” for the service are really separate services that are listed as an add-on because they have a high affinity to the main service. These service add-ons may be subscriptions. Many services probably don’t require Gravity Forms Product Add-Ons, and we could get away with simple product variations, but many do require the robust logic of Gravity Forms.

The problem:
Gravity Forms Product Add-Ons are not products themselves, and thus WooCommerce and other plugins (Subscriptions) has little knowledge of them really other than to modify the final price and thus we cannot create a subscription with the subscriptions plugin.

I have come up with a few thoughts on how to achieve this functionality but am not familiar enough with WC to know which is best or possible.

Possible solutions?
a.) Programmatically check which Gravity Forms add-ons are selected and force add an addition (subscription) product to the cart when the user clicks add to cart. This would work well but has the pitfall of not easily allowing the user to modify any options for the additional product.

b.) Use product groupings to display both products and let the user select that way. This would seem to offer the capability of allowing the user to select options however out of the box groupings don’t show the GF Add-Ons without visiting each product individually and the pricing is strange for us (uses From pricing and selects the cheapest). It seems to lack required product functionality.

Because of the nature of our services we don’t deal with quantities; if someone needs more than one of the same service they need to add it to the cart again.

I have read about Composite Products, Bundles, and Subscriptions but am not certain they will do what is needed.

Any insights or suggestions would be greatly appreciated.
Thanks