Highlight Multiple Cells with Listbox Selections

[Dpage]

Hello,

I am trying to set this pivot table up so I can indicate which Sales Orders(SO) are complete by checking the boxes in listbox next to the table. I used the expression 

=If(GetFieldSelections([Transactions.Ref Number])=[Transactions.Ref Number],RGB(255,255,0)) for the Background Color of the Transaction.Ref Number Dimension (Labelled SO #)

This works if I make a single selection. However, I would like to make multiple selections so I can check them off as they are completed and I would also like to see all of the Incomplete Sales Orders. In other words, the pivot table would NOT collapse when I make a selection but the cell (which matches the SO Ref #'s selected in the listbox) would be highlighted.

[Dpage]

Spoiler

Here are Pictures with One selected and with 2 selected

with 1 selectionwith 2 selections

[Dpage · Accepted solution]

For anyone who is interested, I was able to solve this issue using an expression I found under another thread titled "Highlight multiple values in pivot without removing the other values in the same pivot". the expression I used was posted by Sasikanth. I used the expression  = If(Wildmatch(Concat(DISTINCT([Transactions.Ref Number]), '|'), [Transactions.Ref Number]) and GetSelectedCount([Transactions.Ref Number])>0,RGB(255,255,0),White()) for the Background color of my item.ref number  dimension.  Then I added the set identifier {1} to my expressions so my selections didn't clear the table of un-selected Transactions.  The result is posted below. I may need to add tweaks to get the full function I am looking for but this is what I was looking to do initially.Now I can indicate what is complete by checking the boxes in the listbox.