You can create sets of formulas in the main report like the following, one set for each page footer section, identifying the flags for different subs with different letters:
{@trueA}:
Whileprintingrecords;
Booleanvar flagA := true;
{@falseA}:
Whileprintingrecords;
Booleanvar flagA := false;
Place {@falseA} (along with all other false formulas) in main report report header AND place {@falseA} in page footer_b. Place {@trueA} in pf_a where subreport A resides, and then format pf_a in the section expert to suppress with this formula:
Whileprintingrecords;
Booleanvar flagA;
FlagA = false //note no colon
Repeat for other page footer flags, putting the true formulas only in the section where the corresponding subreport resides. If you need to also use a shared variable because of conditional subreport suppression, then the suppression formula should read something like this:
Whileprintingrecords;
Booleanvar flagA;
Shared booleanvar suppresssubA;
SuppresssubA = false or
FlagA = false
-LB