Q visa family relationship requirements

I want to apply for a Q to visit China. My fiance is a Chinese citizen living with me in Canada. After we get married we will visit her family in China. As I understand it, for my application I will need a letter of invitation from a family member living in China who is a citizen or permanent resident. Will my status as brother-in-law be a close enough family relationship for my wife's brother, who we will visit in China, to write a letter of invitation for me? Thanks for your help.