Communication Help

[Toren]

Last night I was the L in 3 man mechanics.

Team A has the ball in their frontcourt. There is an interior pass to the post that gets deflected toward half court by Team A.

I notice the T has a tipped ball signal up, meaning he thought Team B had hit it back.

At the break, we came together and both the C and me had the ball being hit by Team A only.

How could we have communicated this information during live ball play? Is blowing our whistle the only way? Would you blow your whistle from the L to help out the T in this case?

I felt pretty useless at this moment, luckily the ball never went into the backcourt.