I am extending my Business Service Class, and adding a LOT of information that we store on a 3rd party database for all of our applications. I will be adding several new tabs to it, but one part of our database is vendor information. Rather than repeat vendor information on every application, I am considering creating a new CI Item for Vendor, which includes all the properties I need for the vendor. Then on my Business Service form, I want to add a user picker where the user (or me) can select a vendor, and it will populate similar to the Analysts or owner (just like adding the Business Service to the Incident form), and you can double click that selection and open the Vendor form I will build on the new CI Item for vendor.

I am sure this can be done, as it is simple relationship stuff that already exists between different CIs like the User picker... but I do not know how to create the relationship as I build it. 

Question 2: Once I build this new extension to the business service class (and vendor CI), if I want to import the data to it, how best to do that for new custom properties? I have never done any data imports and I do not do anything with the DB side of it or SQL, so I need advice on this. I thought about using orchestrator, but that will not write to custom fields with a normal runbook will it? I also thought about a powershell script, but I am not that great with Powershell in SCSM Yet.... so looking for the simplest most efficient way to do this.

Any and all advice is welcome! The better I understand these relationships, the more functional I can make my new forms. 

Thanks for any help you can offer.

I should stipulate, my source data can be in Sharepoint list format, Excel spreadsheet or csv.

Q1: New Relationship: You can use the authoring tool to extend the class and the form (here).

Q2: You can use the console import feature of the connectors (XML and CSV link) or do it with Orchestrator (here). I would do it with Orchestrator using powershell only. A lot to read here.