In the above case, is “Toplam” a grid’s footer, or a group’s footer?
In second case those “footer” is just a row of grid with colspan applied, so you can add the new row before or after it (index parameter of add command )
Grouping is an one-time operation. It will calculate sum during grouping, but it will not add any kind of logic to recalculate those values automatically.
It possible to create such kind of logic through custom code though