Using the instructions on the debug window, I created a multi signature address as below:
addmultisigaddress 2 "[\"Address1\",\"Address2\"]" MultiSigAddress
My understanding is that one needs the private keys of Addres1 and Addres2 to be able to spend from MultiSigAddress. Is this correct?
I sent some btc to MultiSigAddress, both Adress1 and Adress2 belong to me and I can go to coin control panel select MultiSigAddress as input. It will send the transaction without any problems.
What if one of the addresses belonged to someone else? How could I use the funds on MultiSigAddress using Bitcoin Core in that case?
Thirdly, the address I created in this case is 2 out of 2. What if I wanted to create an address that is 2 out of 3? How can I create that using Bitcoin Core? Or is that only possible for multi-sig transactions?