I'm a mum of twins boy who are now 3 yrs old. At home, we strictly follow one parent one language. Mum will talk to them mainly in English and read them English stories. Which language would dad say really depends on his mood when he's tired of speaking English, he may use Chinese. Granny communicates in mandarin.
This post focuses the books they favor and dynamic between the boys and their family. I love this method and believe that it would be a treasury for them when they grow up.
Hope I could make it! Let's start from here~