Responses
Actually either you eat them or you inherit them as long as you're Ymir subject, Since his father went missing and probably already consumed his 13 years. And his sons are eren/ zeke (I keep forgetting this kid exist)(づ￣ ³￣)づ
So, Eren really did ate Grisha, I was hoping that he was just missing but still alive. So since you have to eat the person who has titan power to accumulate the power, then he was really eaten...