YOU SAID:

My dog might have gone to the shop, and bought some cars

INTO JAPANESE

私の犬は店に行って車を買ったかもしれない

BACK INTO ENGLISH

My dog could have gone to the store and bought a car.

INTO JAPANESE

私の犬も店に行って車を買うことができたでしょう。

BACK INTO ENGLISH

My dog could have gone to the store and bought a car too.

INTO JAPANESE

私の犬も店に行って車を買うことができたかもしれません。

BACK INTO ENGLISH

My dog could have gone to the store and bought a car too.