Creating Estimate through API is not working right with Avalara Integration

Creating Estimate through API is not working right with Avalara Integration

I am creating a custom function in Zoho CRM that generates an Estimate in Books for the customer in based off of information in a custom CRM module related to the customer in CRM. 

I am running into two issues and they both are related to properly obtaining and associated tax information for Avalara which we use for our sales tax calculations and have since 2017. 

When creating an Estimate in the Books interface, the customer's Entity/Use Code is pulled from the customer data which indicates if they are tax exempt or not. Then each item added to the estimate properly pulls in the Avalara tax code for the item (which is a field in the items module and is present on all of our items.) This process works and everything is great. 

When I am creating the estimate through a deluge custom function in CRM, none of the Avalara information is associated to the Estimate. The Entity/Use Code is always "None" indicating they need tax and items added do not have their appropriate Avalara tax code associated so they are not taxed properly. (Many of our customers utilize an Industrial / Production sales tax exemption which is stored in the Entity/Use Code) 

To date, I have added code to pass the proper Avalara tax code through my script but if something changes, it would need to update the related data being stored in CRM as well as my items list in Books. 

But I have NOT been able to determine how to properly obtain or pass the Entity/Use code for a customer to associate to the created Estimate. 

Has anyone created estimates through deluge / API utilizing the Avalara integration? I am very close to completing my automation and this is one of the last hurdles to go live.