Mr. Venkat first I want to make you clear on the part that no law can restrict you to study anything. You may pursue any studies whether ca cs or cma but the main problem which arises is during employment or practice.
According to the Mou signed between ca cs or cma you should choose only one course as your career either ca or cs or cma. You cannot pursue two jobs at one time belonging to two different courses. Even you cannot choose one in employment and one in practice as it is the breach of profession rules.
for example If you are in job for cs you strictly cannot apply for practice for ca or cma and vice vera. There is a software in the treaty who when you become a member of one course automatically provides information to the institutes of other courses. That is yu may study whatever you want to but can only obtain the membership of any one institute being ca cs or cwa