Every time I overheard my 2 daughters conversation about someone new they met either in school or anywhere I’ll start to poke further:

What’s her/his name?
Where do they stay?
What does their parents work as?

The way you ask was like doing interrogation. I think the girls must be very stressful when talking to you. In the end , I think they will rather keep all the details away from your knowledge. Personally, I'll rather talk more on the activities they do at school, what problem they faced, etc. Let other subjects of talk lead them to spill the beam, if they are willing.

If you worry your kids mix or make friend with wrong group of ppl, on/off whenever the daily condition permit, just give you opinion on the character of of person base on the actual scene happening. For instance, you see a random boy helping an elderly crossing the road, just give remark "one of the quality to look for life partner, taking care of elderly .." indirectly giving them hints. If you see the bad example like mat rempit racing the bike & passed through your car, give remark like "never do this because it will not only endanger yourself but also other ppl, never look for life partner who engage in such activity, the risk to become a widow very high if your partner got killed in the accident, etc".

Children nowadays are rebellious, the more direct you talk to them, the more resistance they will shows it to you.

Agree. Hence, my line of questioning is something like...

1) oh, is he/she a good friend? That's good, if he/she is mistreating you, tell him/her, ok?
2) oh, what did you guys/girls do together? was it fun?
3) oh, how is he/she today at school? (takut demam ke, batuk2 ke and then jangkit to my kid)