Through Sofia's Facebook post it shows that her grandmother noticed her transformation and also felt that she has changed for the better. With that, her grandmother knows that Dorje Shugden is not a demon, instead is a deity. Reason being is that there is no way that when we practice something that is demonic, we can transform into a better person. If we do demonic practices, we would only be a worst person, we would never be able to transform to be a better person and be able to influence the ones around us to do this practice that many say is a demonic practice.
If even H.H Dalai Lama's guru can be practicing Dorje Shugden, it would mean that this practice is correct. Reason being that if H.H Dalai Lama's guru is wrong, then whatever that the Dalai Lama is teaching us now would be wrong. Then that would not make any sense. At the same time, if the Dalai Lama's teacher is wrong, then why should the Dalai Lama go pay his respects at his Guru's residence every time the Dalai Lama goes back to Gaden?