Help me with the script to add a new variable field, into old opened sc-task form

[JOSIPHIA]

this is the code to add the new varialble into RITM opened form already created before I added the new variable in the request form. 

var query = " assignment_group.u_display_nameSTARTSWITHfive9^state=3"  

var variable_sys_id = " Ca9798d3db540650f635a4fdd3961917"  

var grRitm = new GlideRecord('sc_req_item');  

grRitm.addEncodedQuery(query);  

grRitm.query();  

while(grRitm.next()) {  

    var newOpt = new GlideRecord('sc_item_option');  

    newOpt.initialize();  

    newOpt.value = "";  

    newOpt.item_option_new = variable_sys_id;  

    newOpt.order = 20;  

    newOpt.insert();  

    var mm = new GlideRecord('sc_item_option_mtom');  

    mm.initialize();  

    mm.request_item = grRitm.sys_id;  

    mm.sc_item_option = newOpt.sys_id;  

    mm.insert()  

} 

now i want to add the variable into sc_task. please help me with a script.