King Daniel Into Darkness wrote:
There is quite a difference between the Berman-era Trek universe and the TOS one. In TOS, Kirk met androids and shapeshifters, journeyed to the edge and the centre of the galaxy and kicked a ton of ass along the way. Then, in BermanTrek, the only android known is Data (+family) and the only shapeshifters are the Changelings (because apparently "The Dauphin" and "Aquiel" didn't really happen, or someone would have told Odo that he's not alone in "The Emissary"
It's confusing, and I think fair to say that there's nothing they can do to please everybody.
Neither of those episodes seem to provide a likely candidate for being 'like Odo'. Species that are able to (usually in limited ways) change form are old hat in Star Trek, but that doesn't make any of them 'Changelings' in the same way that Odo is. The only serious possibility I can think of is Marta from TUC, whose actual form was never shown. So, even assuming anyone knew specifically about any particular incident, why would they tell Odo about creatures that probably had nothing to do with him or his people anyway?