I've been so successful with using Exiftool that I'm thinking of some other possibilties. Your fault for giving us such a powerful utility. :-)
As Lightroom and Acdsee both save Raw settings to sidecar XMP files and it now seems withing the realms of possiblity to store both sets of data in the Raw file
I'm reworking my batchfiles to copy required fields from these sidecar files to the raw files directly.
Originally your previous suggestion works well but leads to problems particularly when using Acdsee which doesn't retain any Lightroom fields.
Interestingly LR does retain Acdsee settings by copying -xmp:acdsee to it's database.
So if I were to use: