How to make alterations to an already registered FIR

Our case has already gone to FIR but in that FIR there was not mention the name of the person ,who has attack with wood and steel at my father and my 2 uncle on back of head and on my father's hand also break for attack by wood with his family member and his sofa industries emmployee'sand the same person also attack on my mother,my mother's nighty teared the same boy with his father,my question is what to do now?if in the fir there name has not mention in details,who has done what...now How to alterations to an already registered FIR?