You can't break that relation. You can either have a pattern or not. You can dissolve a pattern after you create it, but then you will have to add mates for each component.
You MIGHT be able to make a subassembly of the finger. Make it mated to one of the planes, but let it float in the direction it will move in the chuck. Then make four different configs of that subassembly. Put the first one into the chuck assembly and make it flexible. Fully constrain the subassembly planes in such a way that the flexible finger moves inside its subassembly when you drag it. Then pattern the finger. Edit the configuration of each patterned finger to not follow the parent but be a different configuration. That might work.