Filter by Criteria Issues

Filter by Criteria Issues

Thank you in advance to anyone able to help me with this issue.

I have a Task Form and in that form is a lookup field "AssignTo" which pulls from the Employees Form to have a dropdown list to pick who to assign it to.  Within the Employees Form is a checkbox and the AssignTo has a criteria to filter the dropdown to only show those Employees with the checkbox marked.  That way there aren't a hundred names to scroll through but just those that you assign an item to.

That works fine for what I need.  The problem is on the filter.  The AssignTo filter wants to show all the employees, not just those who meet the criteria in the form.  So it works fine in the form but not in the filter.  How can I fix this?

Also in order to get the email update function working, the AssignTo lookup field pulls from the employee's email but is set to show them on the dropdown list by UserName.    That works fine.  However, in the AssignTo filter it also shows all the employees by their email address rather than by their UserName.

Issue 1:  How do I make the AssignTo filter on the Task List show the employees by the Assigned="true" field from the Employees form?

Issue 2: How do I get the AssignTo filter to show the employees based on their UserName instead of by their email address?