Another members solution;
DMLUSER
User level:Level 1
(4 points)
Apple WatchSpeciality level out of ten: 1
Jun 25, 2021 9:24 PM in response to fieryjack
Okay, an Apple rep helped me figured it out over chat. I'm not sure they've documented this process. Here's how it works.
Open workouts and start your workout, running, say.
You have to let that run for one full minute before the New+ button will allow you to select anoher workout type.
Select New+ then select the next workout you want to do, let's ride, cycling.
Let that go for one full minute then select New+, let's pick rowing.
Now you have three workouts going -- running, cycling, rowing.
To change from one workout to another, hit pause and select one of the the workouts you've already started.
To end them all, select End.
Then scroll down and tap on done.