It wasn’t the Queen who gave birth to the twins, it was the 2nd consort. It explains it in chapter 4. I wouldn’t blame the mother since she’d of course be exhausted from giving birth, not everyone remembers the exact details, especially in these times with not way to ease the pain
How in the heck does the queen not remember giving birth to twins? ┑( ̄Д  ̄)┍
That has to be the most odd plot I have read in a while.