Creating a custom dropdown list for each recipient

Hi all, 

I am new to Adobe Sign and trying to figure out if it's possible to have each one of my recipients for a web form see a custom list in a dropdown list. For simplicity, assume I have two fields, one text field (Vendor Name) and another dropdown field (Contract #). We do not want vendors to see each other's names or contracts, so my plan was to create a custom url for each vendor with 'Vendor Name' prefilled for each recipient and read only using the instructions I found here (https://helpx.adobe.com/sign/adv-user/web-form/url-parameters.html). Based on the vendor name, I would like the 'Contract #' dropdown field to only show the contracts that belong to that vendor. 

Any help would be greatly appreciated!

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