I would think that this is something that is subject to the laws of your country. Familiarize your self with them and I would think that you would find the answer there.
Regarding having to take the MCC and the 14 ATPL exams I think that you are misinformed there. I would believe
that your country would respect the rights you have earned yourself with the old CPL, and not force upon you requirements unrelated to it. Here, were I'm from, the law states very clearly your right regarding this. However we have to maintain our national licence according to JAR-FCL requirements, but that is ok for us because the JAR is less demanding than our old law was - can you believe that?
I hope this helps.