When they do split, you may be able to combine a few of them to make whole pieces again that don’t look bad.
Your only other hope is to use PEG (polyethylene glycol) or Pentacryl to stop the cracks. This is a different approach than denatured alcohol. The DA replaces the water and then dries away. PEG saturates the wood to prevent it from shrinking (so it really is never “dry”). You then lock in the PEG with your hard finish and that should keep it from splitting.
If you’re going to save it, you need to do this now. To prevent them from drying too fast, bring them inside and spray a little water on them (do not dunk them in the bathtub or run a faucet over them). Then, go get some PEG and hope it stop them from radial splitting.
-- "Well, at least we can still use it as firewood... maybe." - Doss
