Inconsistency with CHILD-relations when editing subtasks on multiple devices

When the same task in a tasks list is edited on multiple devices the corresponding ics file of the main task is getting inconsistent regarding the parents CHILD entries. There is no error that can be seen but it makes things a bit unlogical.

Steps to reproduce:

• Create a task in the web interface (e.g. Nextcloud) and sync with devices A and B
• Create subtask 1 on device A and subtask 2 on device B
• Sync both devices. Both subtasks will correctly appear on both devices.
• Download the main task in Nextcloud web interface as ics file.

Actual result:

Main task has only one RELATION CHILD entry to the subtask that has been synced at first.

Expected result:

Either no RELATION CHILD entries, or both.

Further information:

The problem comes from the conflict when the main task is uploaded by both devices.

We can talk about it, too ;-)