Multi-Column Slicing, is it possible?

Hello everyone, new here, hoping to get a bit of help. I'm trying to create a simple table for a group of teachers to track their personal libraries in a shared document. I have made a simple summary tab (book title, subject, owner, tag 1-4, separate columns). I then put it into a pivot table to organize the data. For context: The TAGS are the main concern. They want to be able to add these "tags" or "themes" these books deal with. There may be multiple per each book (hence tags 1-4, each it's own column). For example a book might deal with bullying and diversity. In tag 1 it would say bullying, tag 2 would be diversity, etc. I made the list of tags into a table and inserted a drop down list in each field to standardize the options they can pick.

My issue: On the pivot table I wanted to use slicers as its a very easy, visual way of selecting themes they want. However I cant get all the tags to filter on one slicer as each tag is a different column, even though they're all pulling from the same drop down list. I am not using any formulas here. I have inserted text in the pivot table via concatenatex (DAX functionality). I would like to be able to filter all books that, for example deal with anger, whether it's in the tag 1 column or tag 2. I have tried to create a relationship between the tag columns and a separate tags table, but can only do one column to one column (the others become inactive). When I use the slicer, it will only filter to the active relationship pairing, ignoring the other columns.

I have 3 tables:
Summary Table
Tags (standardized list for tag selection drop down in summary)
Party (grade/age group standardized list for drop down in summary)

Is there a way to get 4 columns to filter at one time? or just a different approach i"m not thinking of?Books-Database-Excel-Snip.PNGBooks-Database-Excel-summary tabSnip.PNG

The underlying problem here is that the tags are spread out over 4 columns. The problem would go away if there was just one column for a tag and if there are more than one tags per book, you'd have several entries per book, one for each different tag.

Then you can build a pivot table that lists each book only once and you can use a slicer that shows all tags.

You mention DAX, so you are using Power Pivot. Load the source data into Power Query, select all columns but the tag columns and use Unpivot Other Columns. That will create the data structure you need.