can I do CS after BBA??

I dont think so you can do as cse is a ug program as well as bba.I suggest you to do CSE first and then directly go for MBA.This can be done and many do it too.All the best

All graduates and post graduates (excluding fine arts) and those passed in the Foundation examination of The Institute of Cost Accounts of India (ICAI-CMA) or CPT Examination of The Institute of Chartered Accountants of India (ICAI) or of any other accountancy institution in India or abroad recognised as equivalent thereto by the Council of the Institute are exempted from passing the Foundation Programme examination. Such students may directly seek registration to Executive Programme of Company Secretaryship Course.

Hope this helps!!!