Need to group 1 pivot table among 30

Hi All, I have a worksheet that has over 30 pivot tables, they are not grouped as they represent bi weekly pay periods. However, I have 1 pivot for WSIB that requires it to be grouped by month. When I group this one by month, it groups ALL the pivot tables. Is it possible to only group 1 pivot table, or is it an All or Nothing scenario?

Thanks
(P.S. if this is the second similar post, my apologies, I am having browser issues)

Thanks