
Not at all! His father wasn't the culprit of Linden's mother and sister's death!!! It was the third prince's (cute blondie) mother and uncle the ones who pushed them away from the Royal Family which led to his mother to commit suicide. That's why Lise is thinking of how to prevent Linden from taking revenge, as he would have to kill everyone from blondie's family and faction including blondie himself (as blondie wants to protect his mother by ascending the throne).
In the past, Linden actually killed everyone but Lise knows Linden and his half-brother actually like each other and get along well too so she doesn't want Linden to massacre everyone from the third prince's faction (as shown in a flashback, killing everyone made Linden lose control and fall into the abyss of depression)
You can try re-reading if you wish, I hope my explanation wasn't as confusing (●'◡'●)ノ

Yes... the emperor actually loved Linden's mother more than the blondie's mother (the empress at the time)... that's why she wanted Linden's mother and the emperor to be apart. She knew that the emperor would probably make Linden the heir because he loved his mother...
I forgot his name that's why I keep calling him blondie but he's good, in the past he was Lise's only friend (before Linden killed him) ٩(๑❛ᴗ❛๑)۶
Wait I'm confused. Didn't the prince want to kill the emperor for revenge against his mother?