Wix Websites - Enable customers to use subscription on two sites

Description

I require the skills of a proficient Wix developer to implement a specific subscription functionality across two separate websites built on this platform. Currently, customers maintaining an active monthly subscription on either 'Nailseadogfield.co.uk' or 'Clevedondogfield.co.uk' are restricted to booking services solely through the site attached to their subscription.
My goal is to modify the subscription logic so that a single ongoing payment provides equivalent booking privileges on both sites simultaneously. In other words, any customer with an active subscription would be entitled to utilize the booking systems present at both Nailseadogfield.co.uk and Clevedondogfield.co.uk during their subscribed period.
The key deliverable is integrating the subscription databases and booking modules of these two independent sites so that a unified customer experience is achieved. Customers need only maintain one recurring subscription to gain dual site access for making reservations.
Ideally, the candidate should possess in-depth working knowledge of Wix's platform and codes along with a proven track record of designing and configuring multi-site integrations on this platform.