Hello , 

as your query is you want to know that if you have done with the admission of the college provided to you in 3rd round of counselling then and you have also paid the college fee then whether you can take part in mop up round or not. 

Would like to tell you that once taken admission in the college seat allotted to you in the rounds of counselling that means that the seat has been freeze by you then any of the ways you are not eligible to take part in the mop up round for participate as well as you have paid the college fee then it might be somehow worrying for you in case if the college doesn't return your fee then in your opinion it will be better to go with the college allotted to you or you have taken admission. 

Thank you.