Then there are the makefiles that expect certain commands, such as changing to a different directory, to not affect other commands in a target's creation script. You can solve this is either by going back to executing one shell per command (which is what the -B flag forces PMake to do), which slows the process down a good bit and requires you to use semicolons and escaped newlines for shell constructs, or by changing the makefile to execute the offending command(s) in a subshell (by placing the line inside parentheses), like so:

install :: .MAKE
      (cd src; $(.PMAKE) install)
      (cd lib; $(.PMAKE) install)
      (cd man; $(.PMAKE) install)

This will always execute the three makes (even if the -n flag was given) because of the combination of the :: operator and the .MAKE attribute. Each command will change to the proper directory to perform the install, leaving the main shell in the directory in which it started.