That macro program looks like it is maintained or provided by the owner of the web site.
Did you get a compiled macro? Or do you have the original macro code? If you have the original macro code, you could modify it yourself to make the desired changes. If you only have the compiled macro, then you will need to contact the original provider of the macro program to obtain updates.
If you have the current starting source code for the macro program, you could modify the source code yourself and make a new macro program which would operate as desired.
It does not look to me like the macro was ever listed in a user group, SUGI or SAS Global forum paper. Nor does it look like the macro program was written by SAS Institute. Generally, macro programs written by SAS staff are searchable from the support.sas.com web site. Since I did not find a reference to this macro program on support.sas.com or in the SAS documentation, my conclusion is that it's not a SAS-written macro program.
So, you need to find the original author of the macro code. Failing that, your choices are to live with the way the macro operates or change the source code if you have it or write a new macro program.