They use different, non-compatible encryption systems. Treat each OS and its MBR/GPT partitions as separate entities.
- You will make mistakes. Data will be lost. So practice using spare equipment. Do NOT use any production system as your test bed.
- Back up your production systems before beginning your multiboot transition. Yes, you will have already practiced on spare equipment, but you may still make a mistake resulting in data loss.
Using multiple drives will be a superior solution.