This is something I've been thinking about a bit as well...
How about this scenario..
I know you have 3 years to complete the CPL/IR after finishing your ATPLs.
What if you did a CPL, and say an instructor rating, but hadn't done an IR by the time the 3 years was up.
Would you be left with a valid CPL, but would have to resit the ATPLs if you wanted to go for an ATPL licence in the future?
Thanks,
Stu