Problems with computed var after mapping and adding new elements to observableArray - knockout-mapping-plugin

Question

I am trying to create within knockout mapping some computed variables. The problem is when adding new elements to the children's children after the mapping, my computed variables don't update with new elements added to the observableArray
Please could you help?
Here is the code, also attached a jsFiddle
Thanks
https://jsfiddle.net/r3pasftb/18/
var data = {id: 45, Name: "Whatever Name",
Stages: [{stageID: 1, StageName: "Stage1", Team: [{Name: "Team1", FeesAllocated: 500}, {Name: "Team2", FeesAllocated: 200}]}, {stageID: 1, StageName: "Stage1", Team: []}]};
mappingTeam = function(options){
var teamSelf = options != null ? options : this;
teamSelf.Name = ko.observable(options != null ? options.Name : 0);
teamSelf.FeesAllocated = ko.observable(options != null ? options.FeesAllocated : 0);
return teamSelf;
};
mappingStages = function(options){
var stageSelf = options != null ? options : this;
stageSelf.StageID = ko.observable(options != null ? options.StageID : 0);
stageSelf.StageName = ko.observable(options != null ? options.StageName : 0);
stageSelf.Team = ko.observableArray(ko.utils.arrayMap(stageSelf.Team, mappingTeam ));
stageSelf.Length = ko.computed(function(){
return stageSelf.Team().length;
});
//I need this value to be updated, but do nothing with new elements created after the mapping
stageSelf.TotalStageFees = ko.computed(function(){
var total = 0;
ko.utils.arrayForEach(stageSelf.Team(), function (team) {
total += team.FeesAllocated();
});
return total;
});
return stageSelf;
};
var mappingOptions = {
create: function (options) {
return new function () {
var self = options.data;
//Here map Stage Array
self.Stages = ko.observableArray(ko.utils.arrayMap(self.Stages, mappingStages ));
ko.mapping.fromJS(self, {}, this);
};
}
};
//Map my object with child and subchild
var self = ko.mapping.fromJS(data, mappingOptions);
console.log(self.Stages()[0].TotalStageFees())
console.log(self.Stages()[0].Length())
//Add new TeamMember to first Stage
self.Stages()[0].Team.push(new mappingTeam({Name: "Team3", FeesAllocated: 50}));
//As you see, non TotalStageFees or Lenght are updated
console.log(self.Stages()[0].TotalStageFees())
console.log(self.Stages()[0].Team())
console.log(self.Stages()[0].Length())