I believe you can only float if you pay the seat acceptance fee for CIVIL and wait for a higher branch or insititute in subsequent rounds. In case you dont get any higher preference, you will always have your seat confirmed in CIVIL. And if you get you higher options, the fee will be adjusted for the same.

For more information and rules and regulations of OJEE Counselling do follow the link below

https://engineering.careers360.com/articles/ojee