Lost Left Hand Dock when Second Monitor Connected

With a second monitor now added to the left of our main monitor our dock, which we like to position on the left hand side of our main monitor has now moved all the way to the left hand side of our second monitor.

Is there a way to have our dock back on the left hand side of our main monitor when the second monitor is not in use? We’ve not found a way.

Does Catalina have settings to control this behaviour?
Is there third party software which can help with this scenario?

macmini 2018

In my experience; the dock is far left, far right of all monitors combined or the bottom of each monitor in use.

Try this:
System preferences > Displays

Select the display arrangement.
Drag the menu bar (small grey bar) to the display you want to be the one holding the dock.

That does not solve it unfortunately. I put the second screen a bit under the first.
It’s not a true solution more like a workaround.

Confirming what @michaelpporter wrote. If you position the Dock at the bottom of the display then when you move the mouse from one display to another, and briefly hover the mouse at the bottom, the dock will switch over to that display. It’s annoying friction, but that’s what works.

Does not work for left- or right-positioned Dock.

The uBar app can be configured to have a dock-link bar on different monitors. I also found uBar as more friction and not all that useful.