YOu can easily suppress groups in the report by using the conditional suppresses in the section expert but that won't impacy the crosstab.
The Group Expert can be used for changing the grouping order, doing top or bottom N options and a few other things but again, no way that I know for it to impact a crosstab. The crosstab acts independendetly of setting up the rest of your report.
It should be pretty easy to do though .Create your most base leved crosstab and get it set the way you want. Copy it and place the copy in the next section up then remove the group you don't want repeat for the 3rd version.
In your section expert then conditionally suppress RH1 where ?parmater <> the paramenter setting you choose to display that one and repeat for PH2 and PH3.
IP Logged
but you might try looking into it to see if it is what you need for future reporting needs.