How can i Set the rowexpand value to hierarchical child grid data Source..

rowExpanding : function(e, args)
{
 var objparam = new Object();
objparam.strUpdatefor = 'FORM';
objparam.struserID = $("#ddlUser").val();
objparam.ParentID = args.parentrow[0].cells['2'].innerHTML;
 corsAjax.get("PageRights/GetFormList", { "data": JSON.stringify(objparam) }, function (objparamData) {
 if (objparamData !== null && objparamData.length !== undefined && objparamData != []) {
 $("#tblHierarchicalGrid").on("igchildgridcreating", "destroy");
 objData = objparamData; 
 }
 });
},

How to set that objData is my Child Grid Datasource...