Exclude items from chart slicers (even if they have data)

Happy New Year everyone. I'm working on a report that pulls data from a data model into a pivot table, which I am then using to create a pivot chart on a dashboard.

The data comes from a transactional database. The qurey pulls all transactions against purchase order numbers associated with a site ID. For each site, there may be many purchase orders related to various vendors, etc. These transactions are important in overall reporting. However, for this particular chart, I'd like to be able to screen out any POs that are not related to the specific vendor(s) who is/are on-site performing the actual work. I was hoping there could be a way I could manually set that up at the creation of the pivot table itself, so I could restrict that data from being returned (see photo below to illustrate where that assumption came from), but that doesn't seem to work.

Capture.JPG

I'd welcome any thoughts or help you can offer on this!
Thanks!!

Hi Richard, Thank you for your response. Apparently I didn't explain my problem very well, so let me try to clarify by providing a more specific example.

Imagine I have a project with purchase orders valuing a total of $10M.
Imagine that 30% represents the value of 10 purchase orders, and are for basic support operations, and 70% of the PO value is split between two contract holders who are actually executing the critcal path work at that site.

Now increase the above scenario to 10 sites.

My client would like to be able to a report tracking TOTAL spend by site (that one is easy, since it's the sum of all purchase orders by site).
BUT they would also like to be able track progress on the two primary contractors at each site. I would like to include a slicer that allows them to look at the report site by site, contractor by contractor. However, the total number of vendors included on the full report is prohibitive - too confusing to put in a slicer. It would be helpful to be able to strip out the vendors &/or purchase orders that are performing non-critical path of work. I don't have anything in the data-source that works as potential filter, which is the only way I can think to manage this at the moment. But I was hoping there might be another way to work around it, within the construction of the pivot table itself, perhaps, that I don't know about.

I hope that provides a little better description of what I need help with. Any ideas?

Andy, thank you for your reply. I want to avoid the VBA route if possible, since it always raises cyber security concerns. But your suggestion got me thinking - maybe I can create a lookup table to add to the data model that serve the purpose. I will play around with that idea a bit...I feel like that might work well.