Wendy,
I understand your feelings too.
Dont upset as it is not worth!!!
I also think that 最緊要唔好比條鎖匙佢地!!!
My parents-in-law dont have our keys and they need to call me before they come over.
Try to talk to your husband to tell your in-laws that they need to call before they come.
One time, they came without notice and I was going out with Ho Yin.
They waited outside for a couple of hours.
After that they knew that they needed to call.