I know that we can create Multi signature adresses using Bitcoin Core but using commands on the console if I remember right , forgot what are the Commands but dosen't matter I can get them again ... However I want to know why when they console gives me back the adresses of Multisig that starts with "3" it dosen't get added to "Receiving Adresses" ?
Mutlisig addresses start with 3 and no, it won't get added to 'Receiving Addresses'.
Basically I should keep that adress somewhere ?
You should save redeem script somewhere safe.
and if I give it to someone is he going to be able to send me BTC or not ?
Send him address starting with 3 you got and he will be able to send you BTC. Whether he/she sends BTC to you will depend on him/her. I can't answer that.
all I have to do is keep it on a .txt file , give it to people and I will receive in my wallet just that simple ?
You will have to save redeem script not only the address just like you save private key.
cause it looks kinda weird whenI don't have it on my receiving adresses and i was wondering ... gracias amigos
Bienvenido!