This reply was created from merging an existing thread: Any way to restrict which additional services may be added after the first choice?

Or restrict products to a service? I don't want to have to write multiple combinations in the name repeatedly, but some are not allowed to be purchased together. 

Example Options 

Room one 

Room two 

Microwave in room 

However, they shouldn't be able to select microwave twice or two rooms. 

Can modifiers assist? 

Hi again @hoteladdict. I moved your post to this thread as they're on the same topic.

There isn't a way to set up services in the way that you're describing unfortunately. Modifiers only apply to items currently, and items don't appear on your Appointments online booking site. 

You can limit your customers to selecting only one service (as mentioned above) but I see how being able to select add-ons during booking would save you time!