Modifying Standard PS Reports

Over the course of a recent project, I have added several custom fields to table proj that are maintained in CJ20N. The customer would also like to see these fields added as selection criteria for three standard reports, and I am having a hard time determining how to add the selection criteria.

The reports are:

S_ALR_87013533

S_ALR_87013532

CJ74

Any suggestions on where to look? Any help would be greatly appreciated.

Thanks

Benjamin Deaver