Yes, you can add hrs, minutes ans secs to a date or time. Here is a small example that adds 3 hrs plus to current time:
B4X:
'Example: Add 3 hrs 34 minutes 12 sec to current time
Dim p As Period
p.Seconds=12841
Dim NextTime As Long = DateUtils.AddPeriod(DateTime.Now, p)
Log(DateTime.time(NextTime))
Dim p As Period
p.Hours = 3
p.Minutes = 34
p.Seconds = 12
Dim NextTime As Long = DateUtils.AddPeriod(DateTime.Now, p)
Log(DateUtils.TicksToString(NextTime))