Just a supplementary thought -

I produced a document for a group I work for, and was then paid by another organisation to adapt it for their own use.

Both versions have been used with no permission or reference to myself by a whole bunch of other organisations. It's happened once or twice in a smaller way with other things I've done.

Not sure if this has relevance or not (maybe it's different), but I am pleased rather than unhappy that use is being made. Where I would be displeased (not cross - only people being made to suffer/left to suffer makes me really cross) is if one organisation tried to sell my work to someone else (I don't think this has happened).