Multientity-subgrid

i have 3 entities that is Individual, Organisation and Group, I have created a entity called Cases, I need to create a subgrid(multi entity subgrid) that displays the records of the three entities in the single subgrid.

I dont want to display it in three different subgrids instead i need it to be display in a single subgrid.

Kindly Suggest

Thanks

Abishek Hari