I agree with @Rajesh , that you need to separate the interaction of the slicer from the table to make this work. There are two ways I can see to do this - the dual table approach that @MK3010 provides in his solution, or turning off the interaction between the slicer and the visual (which will basically render it a disconnected table, and you will lose the ability to filter the table).
I never like to say something is not possible in Power BI, because almost every time I do some clever member pops up with an ingenious hack and proves me wrong, but I’ll just say I agree with the prior posters in this thread, until someone proves the existence of “Schrodinger’s Slicer” which is connected and disconnected at the same time…
Re: your comment about keeping things “neat”, are you familiar with the ability to create custom views within the data model view? For almost all of my reports, I create a custom view with only my data model tables and any supporting tables I want to see. In addition, you can hide these types of helper tables in your report view. The combination of these two practices keeps things neat and makes these helper tables nearly invisible until you want to access them.
I hope this is helpful.