OK, I am getting the picture now.
We still need to know how everything is interconnected.
Now we have both Ethernet and Profibus. How is that connected to the 416-2DP ?
I am somewhat vary of changing the communication setup of the 416-2DP, as it has redundant connections. Is that made by you, or someone else ?
Anyway, I can foresee 2 solutions.
Setup an integrated STEP7 project with all stations. The HMI's can then access all PLCs memory via routing. It is the easiest and most flexible.
Setup S7 connections between the 416-2DP and the 315-2DP's. The 416-2DP can then send the DB to the 315-2DP's by means of PUT.
The bad news is that in both cases, you have to download an updated HW Configuration to at least the 416-2DP, but maybe also some of the other stations.
And since there are redundant connections setup, I think that is only possible by the person that has setup the system to begin with.