Yes, i understand your doubt regarding allotment of seat. 

Yes,you can add colleges for swcond phase of allotment as in the process of allotment of seat 

First round results are declared in which the seat availability is shown after round1 when fees are paid for first round alloted seat.

After that the colleges for second round allotment is to be done. So, you can add colleges for second phase allotment.

So that the second round reaults of seat allotment is shown as per the given day.

Yes you can modify add and delete college of your choice in the date given for second round.