You could use jQuery.extend
to achive this behaviour.
sv.MergeQuestionViewModel = function () {
$.extend(this, sv.QuestionDetailViewModal);
this.init($("#mergeQuestionModel"));
};
sv.QuestionDetailViewModal = (function () {
var el,
_init = function($el) {
el = $el;
console.log('init', el);
},
_render = function() {
console.log('render', el);
};
return {
init : _init,
render : _render
};
}());
var view = new sv.MergeQuestionViewModel();
view.render();
Test it on http://jsfiddle.net/GEGNM/