Her mother-in-law would protect Mu Huan as long as she still had worth. In that case, she would forever be under that wretch's feet and be at her mercy.
In no way was this an acceptable life for her, so she must destroy Mu Huan to the point that she'd lose all her worth and become the mud beneath her feet so that she could step on her however she wanted!
"If not her granny, then what do we use to deal with her?" Mu Kexin truly did not know what other cards they could possibly have in their hands to deal with her half-sister besides her granny.
She really wanted to torment her to death!
The reason for her absolute abhorrence for her half-sister was that the latter outshone her in every aspect.
With them sharing the same father, Mu Huan was born as the Mus' big missy while she was an illegitimate daughter. Although she ultimately acknowledged her roots and ancestors, the other missies of the upper society looked down on her.