Wow!! Thanks that did the trick. I dint event ried that before as I was wondering when I will have the same Summary key , ultragrid will blow up. But it worked. Thanks Mike for the sample. 
Can you please take this conversation out to separate thread so that some one else might get the answer as  this thread title is about drag drop problem?  Anyways, Thanks for the sample.

The fact that you have an unknown number of bands is not a problem, You simply have to loop through the Bands collection inside InitializeLayout and apply the same formula to the same column in each band. You could even give the summaries different keys - perhaps by appending the band index in the summary key.

I don't think that the duplicate band keys will be an issue, either. The formula syntax is not ambiguous, and it's pretty clear that you are referencing a summary of a child band. So the grid should be able to find the right summary.

So I don't see anything that will prevent you from doing this in InitializeLayout just as my sample does.

Thanks Mike for the sample and Thanks for following up.
Sample works well *only* when you know how many bands you will be having in your grid. Like in the sample a grand parent band, parent band and child band.  But as I said that my data is recursive in nature and I will not know how many band will I be having(I do have the MaxBandDepth set to 8 though)  .
I guess I have to write a recursive routine in initialzerow or seomwhere to calculate the summary myself and put it on a cell. But I would still use the summary or Formulas and let ultragrid calculate for me. Let me know if you guys have any more question or if I have missed something. 

Hello ajayk2k1,

Did you have the time to look at the sample? Is it fine for you? Please let me know, I will be waiting for your feedback.