I don't know if Jy Din Shakya's (or the ZBOHY's) claims are true or not. Actually, how could I affirm or deny anyone's claim without having direct access to Xuyun's notes (if there are any), or using other reliable methods for historical investigation?
Maybe I can scan the picture of the letter that Master Xu Yun wrote himself to present to the Ven. Master Hsuan Hua as his lineage successor. But for now here is a translation of the letter. Proclaiming (Hsuan) Wei's wonderful meaning
causes the Lineage's teaching to be echoed far and wide.
The transformation (Hua) inherited from Mt.Ling exalt the Dharma path.
Taking across (Du) the forty sixth, The mind seal is transmitted.
The wheel (Lun) revolves unceasingly, rescuing all the living beings.
Written by De Qing Hsu Yun to be presented to Du Lun Hsuan Hua.
And like I mentioned earliar, if you have a copy of Charles Luk's biography on the Ven. Master Hsu Yun, he will note that there is a great Master named Du Lun Hsuan Hua who the Ven. Master Hsu Yun passes the lineage to.
I also realize that there are many claims from many places that Master Hsu Yun has passed down the lineage to so and so, but there isn't actually any solid evidence. They don't provide the letter of transmission for us to see.