Hi Mahesh
In my opinion, we should get the detail page (if the data is not significantly bigger) data along with master list items. This will give us 2 important benefits. 1. Decreased number of requests 2. Smooth navigation for the end user. If we get the details everytime the user clicks on master list, he has to wait for couple of seconds everytime. Expanded data instantly displays details. This will make the user to feel "delighted" 
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This will not hold good if we have deep entities. In my case, i have only one dependent entity in the expand. It is more probably the user will click on all of the master list. So, when he needs details of all masters, it is better we get them in one shot.
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