i think i don't want to send any document or showing my face when i am playing gambling because i want to be in the dark in gambling games.
They will only start asking you these kind of questions once you start breaking their terms stated from the post above. Just avoid them if you don't want to risk your personal information.
i don't want any of my family member is know that i am playing gambling even if i just playing gambling for fun.
By sending some documents i'm not sure how would your family member find out that your gambling unless they're curious of what you're doing then starts asking questions.