Hi James,
Yes, you may add any new variables relevant to your analysis into ADaM data.
The general rule is to use exact SDTM variable names for variables in ADaM if you do not change a meaning or content of original variables.
In your case it looks like adding some new variables HOSTDTC, HOENDTC, HOSTDY, HODUR, etc. will be a right approach.
Regards,
Sergiy