Does the half marathon and 5k have the same start & finish line?
You’d have a local timing device running Webscorer PRO connected to each reader. You’d post the results from each device to Webscorer.com which will calculate the results as “Time = Finish time - Start time”.
You’d setup the race as having 2 laps as follows:
Record lap times = On
Number of laps = 2
Customize laps names = On
Lap 1 = Mid-race
Lap 2 = Finish
Timing mode = Multi-device splits
Device #1 records = Start
Device #2 records = Mid-race
Device #3 records = Finish