Hello,
So from my understanding you want to narrow down what your current filter is selecting?
Example: Your filter is currently selecting Walls with Type Name containing "Generic", but what you are looking for is to select walls with Type Name "Generic" AND also walls in the "Exterior Walls" Workset?
Edit: If that is the case you would just need to add your second condition in your filter (See image attached)
[Image Source: http://1.bp.blogspot.com/-lVfgo-N5XMs/VcGAcZc1TYI/AAAAAAAAGko/iFrx2HwMLUI/s1600/filled%2Bregion%2Bhi...]