Hello Caetano,
Searvhing through the internet, i found an older post of yours for BADI MD_CHANGEMRPDATA. If i understood correcly, MD_CHANGEMRPDATA is for to nske an MRP element relevant to MRP or not. If you need to add a new element, you should use MD_ADD_ELEMENTS. This is why you suggested MD_ADD_ELEMENTS for LTP scenarios...
Have i understood ig correctly?
Best regards,
Nikos