Custom Sublist for Vendor

I am trying to create a custom sublist with a custom record for vendor to hold receiving documentation concerns. I hae the custom record, with the vendor on the record, an da saved search with the vendor name as the available filter and first item on the query. I am not seeing this field to connect to sublist definition. The fields in the drop down

Next, I want to add to the communication tab. Is that properly specified?

Here is my custom record

here is my search

Thanks for the assist!