Hmm I have done a lot of things to my characters for the sake of the plot.
For example with both Anna and Therese, they’ve both lost children.
In Therese’s case, it wasn’t her first time losing a child, but it still doesn’t mean she wouldn’t mourn her son. I think added to the fact that she lost her eldest son as well as his brother. It really makes her love for her remaining child, Marie-Therese stand out and more understandable since she’s her only remaining one.
In Anna’s case, it’s her third child to die and after she had placed all her hopes on him. I think it’s more devastating to her because while Therese had the entire court behind her, Anna was alone and isolated, although she had Henri and her family. She really felt like she was losing everything she worked for along with her son.