Three kinds of statements
1. Testamentary edict acceded to the throne
Kangxi especially trusted Yongzheng and sent him to the Temple of Heaven to worship heaven. And it was proved by Kangxi's will. See the record of the Holy Father.
2 change the imperial edict to the throne
Replace the fourteenth son with the fourth son.
The imperial edicts are all in Manchu and cannot be changed.
3 there is no trust in taking a position.