>but my form will call the sub form and the sub form also will call
>the sub-sub form. so how to pass so many variables to sub-sub form and
>return those variables back to the top form ?

By subform, I guess you mean a page or a pageframe. Still thisform is the "master form". In the subform: this.parent.yourproperty or thisform.yourproperty. No reason to pass variables, you can always reach the properties of the main form using thisform. If that doesn't work for some reason, you can ALWAYS use properties of _SCREEN.

_screen.addproperty('yourproperty','yourvalue')

If you can do it with global variables, you can always do it with properties of _screen.