I sure agree with CJ4 that I would NOT use the crossmember between the FEL arms (the one where your grapple hydraulic adapters are mounted). That could be a disaster for hydraulic lines. However, if you are talking about the square tube that runs between the quick attach adapters, then I think that one would be fine to use to put a chain around. It actually makes your lift point right at the loader pins and gives you a lot of lift power. I have used that one on my tractor with no bucket. That gives even more lift power.
For the FEL bucket hooks, I think I'd put a reinforcement plate on top of the bucket and then weld on a couple of grab hooks. Many people put a slip hook in the center of the bucket, but your grapple may get in the way of doing that.