ngModel nested directive iterating a object tree

Question

I want to parse a tree into nested directives

PROBLEM :

1. can't iterate inside with ng-repeat and call the same directive again . can't create a tree from model

2. can't get path from root object to traverse to last element ex: usercontent.child.a2.t == '30'

   userContent = {
       t: "10",
       child: {    
         "a1": {
           t: "20",
           child: {}
         },
         "a2": {
           t: "30",
           child: {
             "a23": {
               t: "20",
               child: {}
             },
             "a24": {
               t: "20",
               child: {}
             }
           }
         }
       }
     }
   

   PLUNKR http://plnkr.co/edit/5CG1l68BPTpJzDPnyGE1?p=preview