As far as the facts are stated, all of King Mahendra's legitimate children were born of Queen Mother Ratna's elder sister Princess Indra Rajya Lakshmi. Rumor has it that King Mahendra had Queen Mother Ratna go thru operation in the sly (without her knowledge or consent) so that she would not issue other children thus creating another King Surendra or King Girvan situation. Girvan was NOT the eldest son of Rana Bahadur Shah while King Rajendra's younger wife did all she could not to make Surendra (the eldest son from elder queen) the king. It was Jung Bahadur Rana who insisted on making Surendra the king. (Maybe he respected the monarchy or maybe he did it for himself thinking that Surendra being of dubious mental status would be easier to control than his saner stepbrother). King Mahendra's illegitimate son Ravindra Shah was a noted lyricist. Well, these are all based on history books. And we all know history is bunk as Henry Ford said. So, it's all up to you whether you want to go by the history books and the historians or come up with your own hypotheses or conspiracy theories.