BlockProtection - automatic per-block protection

[xoft]

I've found that there might be some confusion involving friends. Let's say PlayerA builds something and adds PlayerB as their friend, then PlayerB comes and breaks A's blocks and builds something else there. The blocks B builds are still considered owned by A, so A can break them even if B doesn't add A as his friend. Is this acceptable behavior?
The other behavior (B takes ownership of the new blocks) has problems when a third PlayerC is B's friend but not A's, suddenly C can break those new blocks, but not the A's original blocks that B didn't replace.