API: Ability to append reference data without user group

In the API it is possible to upload new reference data without specifying a user group.

However, as soon as the reference data is too large to fit in a single upload, we need to use the "Append" option to add to what has already been updated.  Unfortunately, the "Append" option requires the use of a user group.

In our case, and probably many others as well, we don't separate our reference data by user group, so if it is possible to "Update" reference data without a user group, it should be possible to "Append" to it, as well.

Could this function be added?  At the moment we have to add all of our users into a single user group for the sole purpose of accessing reference data, and this change would eliminate that need.