“TDG and DS are the same continuum, so TDG became DS.
There is a casue and effect realtionship there. The mind of TDG was the substantial cause of the mind of DS, and as Chandrakirti very clearly explains in Madhyamakavatara, the seed can no longer exist at the time of the sprout. So, given that Dorje Shugden exists, we must conclude it is impossible for TDG to do anything at all, as the seed has disappeared to become the sprout. If you believe DS can manifest and function, then it becomes nonsense to say that TDG is functioning.” -Crazycloud
This is getting interesting. The Gelug lineage views Je Tsongkhapa as Manjudshri or emanation of Manjushri. According to the bio of Je Tsongkhapa , Je Rinpoche conversed with Manjushri during his retreat. If we follow Crazycloud's argument , this wouldn’t had been possible.
However, the bio of Je Tsongkhapa is accepted without any challenge. Based on this, I would think it’s completely possible that even if DS and TDG are of the same mental continuum , they can manifest at the same time as they have attained the ultimate nature ,therefore beyond the law of cause and effect .