Hi, I have the following property tree. propset1 { prop1 2 prop2 5 prop3 60 prop4 7 } I am trying to add couple of child trees to this so that the resulting property tree would look like below. propset1 { prop1 2 prop2 5 prop3 60 prop4 5 childset1 { child1prop1 4 child1prop1 6 child1prop1 9 } childset2 { child2prop1 2 child2prop1 6 child2prop1 7 } } I wrote the following code. // Add General config pt::ptree propset1; propset1.put("propset1.prop1", 2); propset1.put("propset1.prop2", 5); propset1.put("propset1.prop3", 60); propset1.put("propset1.prop4", 7); // Add childset1 config pt::ptree childset1; childset1.add("child1prop1", 4); childset1.add("child1prop2", 6); childset1.add("child1prop3", 9); propset1.add_child("childset1", childset1); // Add childset2 config pt::ptree childset2; childset2.add("child2prop1", 2); childset2.add("child2prop2", 6); childset2.add("child2prop3", 7); propset1.add_child("childset2", childset2); However the above code is resulting into below property tree. propset1 { prop1 2 prop2 5 prop3 60 prop4 5 childset1 { child1prop1 4 child1prop1 6 child1prop1 9 } } propset1 { prop1 2 prop2 5 prop3 60 prop4 5 childset2 { child2prop1 2 child2prop1 6 child2prop1 7 } } Can someone please suggest what is correct use of API? /anil