Hi
Sorry to p1ss on your fire but here goes...
Do not underestimate the cost of living in Hong Kong it is crippling. Look at propertysquare.com.hk. You're looking at $20 to $30k for a 3 bed place in areas like Tung Chung or Discovery Bay which are near the airport and popular with gweilos. If you want to live downtown I recently saw a tenement (yes it was advertised as a tenement) on said website, a bargain at $20k a month in Wanchai.
On a SO salary and family to support you will in all seriousnesss be on the breadline.
be aware that there is almost no such thing as part time work for Mums here in HK. It's all or nothing mate. Most remain full time mums even though they desperately want to work, part time. Unless her skillset means she can do freelance it's a tough call. Basic part time jobs like shop assistant at your local 7/11 are not worth getting out of bed for.
Positives: HK is a great city and good quality of life, low crime, it's dynamic exciting and the expats are a nice bunch. Locals are very family friendly. Beer from supermarkets is plentiful and cheap. Warm 9 months a year.
Do your homework thoroughly, read posts on here and on asiaxpat, you nail the SO job you know what you are getting yourself into. Good luck.