How to call subscreen into subscreen area in screen painter?

In my program there are two subscreens. The second subscreen to be displayed only if check box of first subscreen is ticked. How to do pass check box variable in flow logic.

Flow logic coding is given below.

3500 :Main screen

3600 :Subscreen1

3700 :Subscreen2

c2 is the variable for check box

if c2 = c_cross then only second screen should be called.

PROCESS BEFORE OUTPUT.

MODULE STATUS_3500.

MODULE TEST.

CALL SUBSCREEN: SUB1 INCLUDING 'Ztest' '3600',

SUB2 INCLUDING 'Ztest' '3700'.

PROCESS AFTER INPUT.

MODULE EXIT_MOD AT EXIT-COMMAND.

MODULE USER_COMMAND_3500.

CALL SUBSCREEN SUB1.

please help.

anu