If LTD interested has already deducted CPP-D estimates from my disability check to force me to apply for CPP-D, will they be required to start paying the full amount if Im denied CPP-D?

Typically yes, once you show proof that you properly applied, and were denied, they would no longer have a basis for deducting the theoretical CPPD payments. That said, I would need to see your policy to give a proper opinion on this. Also, under some policies, you would have a duty to appeal the CPPD denial as well.