Another way a subordinate can be orphaned is by one phase commit.
1. Enlist a single proxy resource at TM1
2. Propagate to TM2
3. Enlist two resources at TM2
4. Return to TM1
5. Commit TM1 thinks there is only one resource so does a one phase commit
6. Propagate to TM2
7. TM2 knows there are at least two resources here so prepares resources
8. Crash at TM2
The resources prepared at step 7 are now orphaned