Hi Ananth Maruti,
If there is more than one feasible successor, then surely it will be listed in the topology table of EIGRP. Please remember the forumla: to have a feasible successor then the Advertised distance of feasible successor should be less than the Feasible distance of successor.
For the 2nd part of your question, if the network in converged than the calculation of successor & feasible successor(s) is already done. In this case, if a successor route goes down, then the feasible successor takes over. In case the topology table had another feasible successor then it will remain in the topology table.
They will be a possible new feasible successor if the network has been changed such as adding a new router in the EIGRP network which has a route to the destination network which complies to the formula that I have listed above, then in this case a new feasible successor will be added to the topology table.
I highly recommend that you read this lesson for more detailed information: Introduction to EIGRP
Hope I could answer your question.