I wish to extend the DataGrid control, substituting the table link that appears when i expand the rows clicking on '+' sign, with another datagrid.
This is like having a treeview of rows:

---Name Surname Address
|
|---Tel1
|---Tel2
|---Tel3

+--Name2 Surname2 Address2
---Name3 Surname3 Address3
|
|---Tel1
|---Tel2

+--Name4 Surname4 Address4

How can i start to do?