Merge cells horizontally in RTF output using proc report

I am trying to create a summary row above each group in my data. I have 2 questions:

1. How do I merge the first 2 cells horizontally (the ones in red below) in the summary rows.
2. How do I remove the duplicated F and M in the Sex column (at the moment I can work around this by changing only those cell's text colours to white, but hopefully there's a better way)

The output is an RTF file, and I'm using SAS 9.4 - the desktop version.

Is this possible using proc report?

Code:

options missing=' ';
proc report data=sashelp.class nowd;
    columns sex name age weight;
    define sex / order;
    break before sex / summarize;
run;

I don't think you can merge cells in the summarize line.

Some trickery with compute blocks and call define can alter the cell values and appearances.

For example (Just J names for smaller image):

proc report data=sashelp.class nowd;
    where name =: 'J';

    columns sex name age weight;

    define sex / order;
    define age / sum;
    define weight / sum;
    break before sex / summarize style=[verticalalign=bottom];

    compute name;
      * the specification of / order for sex sets up conditions in the name value
      * that can be leveraged in the compute block;

      if name = ' ' then do; 
        * a blank name means the current row the compute is acting on 
        * is the summarization row;

        * uncomment if stat is not obvious or stated in title;
        * name = 'SUM';  

        * 'hide' border for appearance of merged cell;
        call define (1, 'style', 'style=[fontsize=18pt borderrightcolor=white]');
      end;
      else do;
        * a non-blank name means one of the detail rows is being processed;
        * blank out the value in the sex column of the detail rows;
        * the value assignment can only be applied to current column or those
        * to the left;
        sex = ' ';
      end;
    endcomp;

    compute after sex;
      * if you want more visual separation add a blank line;
      * line ' ';
    endcomp;
run;