The grandma was introduced as a strict guardian figure, and now that the mother was introduced as an even more controlling figure the grandma is scared? Come on.
Also agreed with
@sharethepudding, this junior feels really unnecessary.
I'm sure the mangaka has a reason for introducing this drama (raising the stakes and getting to Shiki's backstory) but it feels weirdly slotted in right after the confession. Not enjoying it al all, can't even really enjoy Fuyuki's different clothes and bubbly character because they aren't the focus right now, sadly.