On my iPad (IOS 11.0.1, iRealPro 8.0.2) I create a new song, add it to an existing playlist.
Then I make a backup, taking all defaults, and email it to myself.

On my iPhone (IOS 11.0, iRealPro 8.0.2) I get the email, touch & hold the attachment, choose iRealPro.
An import seems to happen.
The new song gets imported, but the existing playlist is not updated with the song.

Thanks for any advice....Lyle