-犬はどこにあるか?
-私は犬を食べた! そして, 私は君の亀を食べた!
-亀の肉は美味しいです!
-それは君のお母さんが言ったことです
!
Both speakers say the first phrase colloquially and the second one politely. Perhaps you should keep it consistent. (Either one, or both)
either:
- inu wa doko ni
imasu ka (iru -> living things, aru -> inanimate things)
- tabe
mashita! kimi no kame mo tabe
mashita!
- kame no niku wa oishii desu!
- sore wa kimi no okaasan ga itta koto desu
or:
- inu wa doko ni iru (ka)?
- tabeta! kimi no kame mo tabeta!
- kame no niku wa oishii!
- sore wa kimi no okaasan ga itta koto da
or:
- inu wa doko ni
imasu ka
- tabeta! kimi no kame mo tabeta!
- kimi no niku wa oishii
desu!
- sore wa kimi no okaasan ga itta koto da
1) Pronouns aren't used that extensively in Japanese
2) I would avoid "kimi" if the speaker is talking politely. I'd use name-san.
3) I would say "kimi no okaasan mo sou itta/iimashita" in the last sentence.