Hi Praveen, you can achieve your requirement as follows...
--> Source: Data Transform (say: LoadInterfaceConstants)
In Data Transform, load results from Decision Tree as
Param.returnValue = @(Pega-RULES:DecisionTable).ObtainValue(tools, Primary, "MapInterfaceConstants", false)
where MapInterfaceConstants is your Decision Table
In your Decision Table, configure the Result Actions as .Interface(<append>) [Where Interface is the pagelist].