JAFO, isn't it clear? The apostrophe can indicate possesion or ommission but with a noun cannot accompany a plural.
Possesion, The TFO's rubbish - Rubbish belonging to the TFO.
Ommission, The TFO's rubbish - The TFO is rubbish.
Plural, The TFOs rubbish - Collective rubbish belonging to many TFOs.
You are correct in your last post, however you are wrong by previously saying, "the apostrophe in TFO's is only required if you are indicating possession by the TFO".
(all of our TFOs are trained, as are all of our TFOs' pyluts
)