Possibility to book add-ons

I will start offering 20 minutes LED (phototherapy) sessions for 70€.
But I would like customers to be able to select a LED session as an “add-on” with every service I propose (Hydrafacial, botox, microneedlling…). And in this case the LED session would be 35€ instead of 70€.
I wanted to configure that in the software without having to configure each and every possible “bundle” (hydrafacial+LED ; microneeedling+LED ; botox+LED…) so that the customer, at the moment of booking, can choose the LED session as an “add-on” that will automatically add 35€ to his booking price.
But I was told it was not possible. I have to create a new service for each bundle. Which make the online booking portal much less readable for the client !


Thank you very much for your suggestion.
We have taken it into consideration, and what we built so far is the option for a client to add more services to cart - bundling is planned down the line: