I'm still not quite sure I understand how this works but a friend of mine has written a programme that will help anyone struggling to format bibliographies and footnotes according to the SBL style. Free download is available here. Thanks, Steffen.
He assures me it integrates with Nota Bene too!

Thanks for the plug, Ros! :-)

To explain how it works a bit...
It's a database of citations: you give it the bibliographic info for each work that you're citing, and keep it there for the rest of your life. It generates footnotes and a bibliographic entry correctly formatted for that entry. You can select a subset of your citations for a particular piece of work and then export an RTF file with the footnotes and a bibliography ready for cutting and pasting directly into your work. (e.g., this is the RTF that has all the example entries in SBLHS 7.2.) You can save and edit each subset, again for ever.
It does this by having a set of entry forms that cover almost every type of work that can be inferred from SBLHS section 7.2 and a few from 7.3.
Nota bene integration: I find that Nota Bene doesn't cope well with SBLHS and I need to use Alt-Cit in Ibidem all the time. This application produces Alt-Cit fields that you can simply type into Ibidem.
I really HTH!
Steffen