When performing an entity upsert via automations, API, Terraform, GitHub Actions, etc, any relationship values are overwritten with that specified on the upsert request. This makes maintaining "many" relationships non-trivial, as now the caller must: Fetch the current entity state Extract the relationship which are to be modified Manipulate the relationship arrays Perform the upsert API call Notice the above requires 2 API calls (GET and PATCH) - meaning that, in any scenario where it's possible to have multiple jobs running in parallel (e.g. automations, event-driven workflows), we also now need some form of "transaction locking" in place, to ensure we don't end up with relations being overwritten from a race condition.