Hi Nabia,
Thank you for your interest in Syncfusion Products.
I am afraid that I am not able to reproduce the issue - 'GridGroupingControl1_RecordExpanded event is not getting raised'. Also I have created a simple sample to test this issue and it is available in the below link.
http://websamples.syncfusion.com/samples/Grid.Web/6.4.0.15/2687_GrandChildTable_Template/main.htmPlease have a look at the above sample and if still the issue exists, could you please try reproducing it in the above sample and send us the modified sample so that we could sort out the cause of the issue and provide you a solution?
Thank you for being patient and please let me know if you have any other concerns.
Thanks,
Rekha