Is there a way to know if a particle is acting as a wave or a particle? Alternatively, if an entangled particle was already measured?

A - Yes

So any experiment over an entangled particle that let you know if they are coherent or decoherent, so would let we know that the distant particle is same "state" (coherence or decoherence), so independiently of any quantum state measured, having detected that "the wavicle has been measured", let you send information coded as decoherence time intervals.

B - No

So, does still have sense to talk about a coherence/decoherence "state" if there is no way to detect it?

EDIT

The wave has his meta-existence as a probability of a detectable particle interaction, but.. if there is no way to know about the system coherence or decoherence -before- it have "expressed" his behaviour (it's done always as a particle) then we could say that coherent state is never detectable?, I mean if you have measured a photon by a detector, you already know coherence is lost, but with engangled particles A, B, if you decoherence A, then what happend to B? only we could know that there is no "random"(umpredictable) value anymore.. then could we know if a particle is entangled with other? or explicitly could we know if a particle was measured or decoherenced from another entangled partner ?

Fantastic way to say it: "Suposse you are employed to discover if our entire world is being spied from other distant world via entangled particles and the random we see (and its subsecuent evolution) was already known via an engangled model of our world, so.. there is a way to know if someone had got access from a distant engangled particle?, or there is no way to know if any measured value was already determined or is the current experiment where it's first known and fixed (and last years as a lab note in a yellow paper..) or was the experiment just redundant, because the value was already known in an entangled distant experiment (and by a distant world, with beings laughing at our surprise) it doesn't matter if the value is random, anyway is a known value, and they saw it first"