It can't be done. The DVD remote will be single frequency for that device only and the LG remote for that LG Blu Ray (or series) only. Companies don't make cross-control between makers easy. The only exception is cable and satellite boxes to allow their remote to also control the television.
If you have lost a remote or it doesn't work, this is the answer
https://www.fixya.com/support/r29872378-universal_remotes_no_facsimile_remote
..
It appears to be a model made for the India market.
https://www.google.com/search?q=lg+dsi+8555+manual
This is the only service manual that is related. If the display is not working, look on the back of the display board for a split or bulging electrolytic capacitor.
Encompass Parts
https://research.encompass.com > ZEN
PDF
This manual was prepared for use only by properly trained audio-video service technicians. When servicing this product, under no circumstances should the ...
109 pages