Add a middle name

[SophieLiu]

I'm wondering how can I add an English name as my middle name, i've searched some information in quebec "name change" website, but it says i should apply it with a form and blabla, still have to do a lot of work. I don't want to change anything, but just add a middle name.
I'm just became a Canadian Citizen this week, and working on my Canadian passport application, so should i change it before apply a passport or after? and How should I add the middle name.

PS: I didn't use my Chinese name for a few years, but only in exams or when i have to sign something, so I really want to add a middle name.

Thx.