As an agent for yacht charter, I'm using Zoho CRM and Books.

For every yacht charter/event sale, there is a purchase of that yacht charter event through one of hundreds of suppliers. It would be nice to easily link the sale together with the purchase. A yacht charter sale is always purchased specially for that particular charter. When a client calls in asking about his charter, I need to easily look up the purchased, easily find from whom the charterer were purchased from, email dialog, etc. 

Could you guide me step by step how you recommend this to be registered in Zoho?