Tableau: Creating Dynamic Filter to exclude names

I have been working on this for the better part of the day and would like to crowd source as I must just be missing something simple.

I would like to use a parameter control to create a dynamic filter that would exclude the names of individuals that have already participated in an event. For example in the following list of two fields:

Name-Event Name

Carl-Agriculture

Carl-Agriculture

Carl-Agriculture

Jodie-Business

Jodie-Agriculture

Jodie-Agriculture

Pam-Business

Pam-Business

Pam-Business

if the parameter was set to Agriculture, only Pam would show up on the list, and if it was set to Business only Carl would show up. This list will help stakeholders send invitations to potentially interested parties.

I have tried so many calculations including the parameter itself in IF statements, IIF statements, CASE statements, etc. I've also tried creating a second calculation to work off of the first but am still striking out.

Any ideas?