ProSoft MVI56MCM Module - Dev Address

I am trying to set up a Dev address in a ProSoft MCM module. This module is acting as the master. The Modbus of the slave address is 7566 in a holding register of 3. I noticed in the manual when setting up the Dev address it references 40001 as the starting point with a 00001 offset. In my case my address is not in the 40001 range so i simply subtracted 1 from the 7566 address to get 7555 as the address. Am i correct in this thought process? I do not have much control over the address in the slave as it is configured by another department to their standard.

Thanks,