Yes, you can (at least technically) add to SpecificContent - it’s a dictionary of string, object.
myTransaction.SpecificContent("myNewEntry") = "this is a test"
From that point you can access it just as if it was there from the start.
Do note that you need to pass your QueueItem as an In/Out argument for that to work and importantly that these additions will not be reflected back to the Queue itself (so no visibility of it from Orchestrator).
That was a great question though, I can definitely see some good uses for it, thanks!
UiPath is (I’m not an employee ) - the Progress and Output fields.
Not exactly the same, but could be used for similar purposes with some serialization in-between.
What are you trying to do dare I ask? Sounds like you may be messing around with new queue items which don’t really exist which sort of goes against a fundamental aspect of UiPath…