Tax audit

An assessee has 4 propreitership firms. all firms having turnover over 1 crore for tax audit purposes. whether he is liable to one tax audit for all firms i.e assessee wise or liable to 4 tax audits i.e bussiness wise. how much form 3CD filed by CA. please advise me...

And also if he appoints one CA for his 2 firms and another CA for his another 2 Firms then how the form 3CD uploaded (one or two or four).....