Lost and Stolen items

Returning money that one had taken mistakenly in childhood

Q: When I was about 7 or 8 years (now I am 30 yrs ), I was at my uncle's place where I took some halalas (coins) almost 3 saudi riyals, (not in term of thief). On the way home my father asked me from where did I get this? I didn't want to dishearten my father so I spoke a lie and said that I took it from my house. It was almost 23years ago. I still remember this as I did a big sin. I also gave sadqa of 30 riyals to give them sawab. Actually, now I am not in the state of giving money back to them as I am far away nor can I talk about it. Can you please give me a solution.

Returning something to the rightful owner

Q: Thirty years ago, when I was a child, I found a gold necklace. My sister took it from me and kept it. Two months ago she returned the item back to me saying she is not entitled to it. The local police law states that if you find something you must hand it in to a local police station and if no one claims it within 28 days then it becomes legally mine. I handed it in to the local police station and no one claimed it. I couldn't say I found it thirty years ago because I might have got into trouble for keeping it so long. Obviously no one claimed it so the police have said I can keep it. I don't want to be sinful so what should I do with the necklace?

Warning someone about being deceived by a certain person

Q: I have given some money to a person who promised me to give me back on Wednesday but he didn't, then he promised to give me Friday and he broke his promise again. Likewise it is more than a week now and I still did not get my money back. I fear he might have tricked me to take money from me and he actually didn't need it urgently.

1. My question is that he also knows my brother and he may ask my brother for money as well and he do the same to him. Can I inform my brother about this so that he is aware of the situation and he does not get tricked?

2. If I complain to my brother about him then this will this be counted as back biting (gheebat) and I should not tell my brother?