nested datagrid issue with collpase issue

Question

hi, i have an nested datagrid( which is of three datagrid) .

so once i click my first data grid i get the second data grid rows( expanded).once i click the rows of the second data grid third data grid is been show( expanded).

which is

but once i click the row of the first data grid which i had clicked earlier all the rows are now Collapsed of the second and thrid data frid which is fine

but once if i click the same row again then the rows of the third data grid along with the 2 data grid is also shown . same ar eariler

but that should not happen right because still i haven't clicked on the rows of the second data grid then how come we are showing even the third data grid values to