I have APIs set up so when a person/business creates an account on my website a new customer is created in Zoho Subscrions and I get the Zoho Subscription customer_id from the response which gets added to a custom field on my website.

When a customer is ready to sign up to a paid subscription, they can click a button from their account dashboard on my website, which will bring them to the hosted payments page passing some customer info to the hosted payment page. 

Is there a way to pass the Customer ID to the hosted payments page so that Zoho Subscriptions knows it is an existing customer that is subscribing to a plan, and not a new customer?