Thought it's a late response,
Seats available in a faster route than Sanghamitra, if you are able to depart at 22:10 on 8th July.
Book tickets this way,
8/7/2013 22:10 Train 12649, YPR - KCG AVBL 244 (Runs mostly on time)
9/7/2013...
more... 10:00 Train 12791, SC - BSB AVBL 11 (BSB is GN quota and ALD is PQ) Alight at ALD. Fare difference 30 rs per person.
Book Now if this is feasible to you...
Else the same can be done for journey starting 10/7. train 12649 doesn't run on 9/7. If you think 12649 doesn't have sufficient gap, you can take any of 12592, 12786, 12429 & 12736 on 8/7/2013. Except for 12786 & 12640 which goto KCG and rest all goto SC so there won't be any hastle to transfer between KCG & SC for onward connection to 12791. Transfer between KCG & SC also is easy unless you have heavy luggage as there are plenty of connecting local MMTS trains in between trains. Choose per your need.
Hope my answer helps you resolve the issue.