Or giving them a bogus "previous block hash" so they're not anchored anywhere in the chain at all.
small question... is that possible ?Sure-- it has to be possible, there is no guarantee that you'll see blocks announced on the network in order. An orphan block may just be one that you can't connect to the main chain yet because you haven't seen it's parent yet (maybe you're downloading blocks and haven't got them all yet, or maybe a miner got lucky and only needed eleven hashes to build on a block and you see her block before the parent because of network delays).