There is a not-so-well-known function in the ODB to write protect some keys. You can do

odbedit> chmod 1 /Equipment/HV/Demand

which will write protect your Demand values. You see that by doing

odbedit> ls -ls

where you only see a "R" at the right end instead a "RWD". I haven't tried it yet (so better do a dry run yourself), but that should prevent an odb load to overwrite your demand values. To change the values, put some logic on a custom page to unprotect the 
values, change them, and then protect them again.

Stefan