Your explanation was perfect. Thank you so much. I wrote some dialogues. Could you please check whether they are correct or not?
Adam: My phone's cover is broken.
John: So is mine.
John: Mine is too.
Adam: She has a a big house.
John: So does my mother.
Adam: My car is red. What about your brother's?
John: So is his.
John: His is too.
Adam: My manager is unbearable.
John: So is mine.
John: Mine is too.
Adam: My books will be delivered soon.
John: So will mine.
John:Mine will too.
Adam: My watch broke yesterday when we played football.
John: So did hers.
John: Hers did too.
Adam: My phone is not old.
John: Neither is mine.
John: Mine is not.
Adam: His books are valuable.
John: So are mine.
John: Mine are too.
Adam: My sister is not ready for the party.
John: Neither is my sister.
Adam: I do not like watching TV.
Adam: Neither do I.
John: I don't, either,
Can I say 'I don't either'?