Needs advise.. plss help

dear all,i have one confusion, i am preparing for 1st group, though i have taken coachings for ISCA and i also want to give exam of isca,as i have strong preprtn of this subject, but havent taken classes for other subjects of group 2, i am targetting for exemption in isca but not able to score 30 40 in rest of the subjects of grp 2..... can i just sit in the remaing 3 papers of group 2. my ques is that " AGAR COST DT IDT ME 0 V AAYE AUR ISCA ME EXEMPTION AAYE TO KYA ICAI WALE MERE US PAPER KO EXEMPT KARENGE...???"