I had the same problem. Long trains with engines at both ends and across multiable blocks. I had a friend build this for me, this is above my pay grade. Works great, same system as you, DCS, 4 blocks and four bricks. All blocks shut down. So it is doable, just need someone to build this for you. This was built off site then installed.
PS when I asked this same question a few years ago on this forum I was told it can't be done.
Clem