My employer sent me 2 T4s and one Releve 1 for the same job, since I can't enter manually the amount in the Box C, there is no way for me to enter the correct information

I tried to enter both T4s and skipped Relevé 1 for both, then I started a new T4, selected QC, skipped it and went to the Relevé 1.

I also tried to enter the main T4, then to enter the Relevé 1 but again, the amount in box C cannot be changed and is too low.