Stacked automount dependencies

[shiva@xxxxxxxxxxxxxxx (Kenneth Porter)]

--On Friday, March 30, 2018 2:25 PM +1100 Michael Chapman 
<mike at very.puzzling.org> wrote:

> This probably isn't going to work the way you want. Starting the share1
> automount will itself cause share0 to be mounted, since systemd needs to
> ensure that the share1 directory exists, and to mount an autofs
> filesystem at this directory.
>
> If you stack automounts in this way, the "inner" automount essentially
> keeps the "outer" mount permanently in use.

That makes sense. So what I really need is a way to start the nested 
automount unit when the outer mount unit starts. The app will touch the 
outer mountpoint causing it to mount and starting the inner automount unit. 
The app may then navigate to the inner mountpoint and cause it to mount. 
But I don't need the inner automount unit to start at boot. It just needs 
to start when the outer mount completes.

So what can I put in either the outer mount unit or inner automount unit to 
make the inner automount start when the outer mount completes?