Wagetype config for india payroll

Hi All

I have one requirement wherein i have to configure variable pay .

Scenario is variable is some  percentage of CTC . we have one wagetype for CTC.

Issue is that this percentage changes across the payscale groups .

E.g. payscale group 4 &5 ---- 20% of CTC

Payscale group 6&7 --15 %  of CTC

Please guide and help.

Thanks
Seema