Hello aspirant,

Hope you are doing well,

If you are not happy with the allotted seat in end round of medical counselling then you can upgrade( slide or float) If any of the preceding choice's  seat  becomes vacant then you will get than otherwise you get the allotted seat given to you from the previous round. But under any circumstances you can't get the receding choices after you are allotted a particular option. So if you don't get anything new college or department in the next round then you will get the seat of the previous round.

Mop up round is basically the last round of counselling process after the ending of all rounds of counselling, it happens with the left over seats . Students take part in this for the remaining seats from the main parts of counselling. Unique and positive thing about this round of counselling is that a particular student can re-sort re-arrange and re-build their choice filling list in this round. It is the last centralised counselling processs before the decentralized counselling process by individual institutes.

The below link may be helpful for you to know more information,

https://medicine.careers360.com/articles/neet-counselling

https://medicine.careers360.com/articles/neet-counselling-faqs

Hope this information helps,

Best of luck