sgerrard, yes I would have as many relationship as I would have separate entities. So my Attachment entity would have a relationship to say ImageAttachment , VideoAttachment, audioAttachment etc. in the case of for example a video the relationship for Image and audio would be nil and vice versa.
It might end up being identical under the hood I should look at that to see when to use which method or if I should use the parent entity approach going forward. I like the idea of not having to maintain all the relationships but I didn’t know if there was any cons to the approach/