Yes, that is unfortunate, and I hope to fix it.
The problem is that the database can become large, several GiBs, so simply adding it could cause some very large “extra” files to be uploaded.
We could work around that, but I think that it is more a workaround for a problem that is not supposed to be there.
If you want to try something like this, you can use the --control-files option to inject files into the dlist files. You can restore from the commandline using the restore-control-files command.
If we go this way, I would prefer that we do some kind of incremental/differential backup of the database data instead of just copying the database. The reason is that the database layout is wasting space in an attempt to be more efficient, and I would like it to be less space consuming.