@fabiaville:
Emperor known Cedric as a upright man, since Emperor himself did many bad stuff, he cant trust Cedric. But now there are Tia, daughter of Miraila, who also was hate by Cedric, yet Cedric accept Tia. That mean Cedric do have tolerance for people with bad ties, if they can make him like them enough. This is a good enough reason to use Cedric, especially when the military force of Cedric is valueable to both Emperor and maybe Lawrence in future.
On Tia matter, she has done nothing in the past that harmful to her mother, so far show intention to get better relationship with Emperor, even get his daughter Eunis to make up with him, not to mention may get Cedric closer to his side. As Emperor, he hold the biggest benefit source, so he can be sure that she will not do harm to him, or Miraila or Lawrence, without good reason. And surely Tia did love her mother and brother a lot in her last life.
About Miraila, problem is she do not plan that far. She hit her daughter because she is angry. She hold her daughter because she feel insecure. Actually she is now "made" a noble, as the wife of the late Rozan, her money source can be the Rozan, or from the Emperor. The value of Rozan house to her is not high. If she do not have Emperor, she may cling to Rozan house. But Emperor want to use Rozan house as bribe on Tia to lure Cedric to him, Lawrence even more so, Miraila still the love of Emperor, with his only son, have the whole country noble and money backing her, why hold on to Rozan, when both her "important man" have other use for it.