Embedded File AOVs and Lightgroups

[ackdoh]

The current setup for render layers according to https://planetside.co.uk/wiki/index.php?title=Render_Layers_and_Render_Elements seems to write out all AOVs as separate files and folders. Is there a way to embed the AOVs directly into the .exr file for easier management? 

Also regarding Lightgroups, they turn them on and off per light group used in the render layers. Wanting to just adjust the sun or adjusting another light, will require a separate render from what I'm reading. Could that be written out like the AOVs where it doesn't take another "pass" hit for rendering but just spit out as an AOV or also embedded into an exr such as what Redshift or Renderman would do?

[WAS]

Alpha embedding into TIFFs and EXRs would be great too. Having to assemble things per-frame is costly.