/multiline works for many things but for somethings like a mass group /invite chain it simply doesn't for some reason. It says they are invited but they dont see it. It's still helpful though on saving lines in a macro since most things work fine.
All other things aside, don't you think it's a bit irresponsible to post code you clearly have no idea the stability of that involves instantaneously grabbing an item from inventory and destroying it?
Just saying, what seems to work (shakily..) to you, does not always work the same on other clients, latencies, mq2 builds, etc.