Responses
Pretty sure in the early chapters she stated giving birth to them they stole her powers.
Rendering the contract void.
No powers= no ability to be linked.
Yes yes (☞ﾟヮﾟ)☞
Anyway, from my theories;
She said that her life and the emperor are connected together as one. If one dies the other will die too. So, on HOW she did it was taking the emperor's blood to make contract(quite make sense to use this word) .
And not only that, she also KEEPING the blood in her body JUST to make babies. And sooo, the moment the babies came out, they also took along the emperor's blood.
When someone make contract for example master-slave relationship, the blood must be fusing with each other blood. Well IF their world have the same concept.
Sorry for English