They listen to the mixes at the lawyers' offices and if happy the lawyers release funds to me and recordings to them simultaneously.
This could of course be more procrastination, and does require me to do more work before I see any money. But I would trust the lawyers not to release the recordings without my agreement - it's a striking-off offence if they did so!
I'm minded to do it unless anyone wants to talk me out of it?
Dynamite with a laser beam...