YOU SAID:

the boy was a girl but the girl wore a red dress to the dogs party

INTO JAPANESE

男の子は女の子でしたが、女の子は犬のパーティーに赤いドレスを着ていました

BACK INTO ENGLISH

The boy was a girl, but the girl wore a red dress at a dog party

INTO JAPANESE

男の子は女の子でしたが、女の子は犬のパーティーで赤いドレスを着ていました

BACK INTO ENGLISH

The boy was a girl, but the girl wore a red dress at a dog party