How do I use a HDV on a parameterised page?

Hi Mel,
I'm going to assume that you mean a Draw HDV widget on a parameterized page. There's a trick to it...
First, widget properties can't use expressions the way tag parameters can. At least not in the UI. If you're prepared to edit the page code, then the sky's the limit.
But in this case, that would be necessary only if you want to parameterize the selected Group of the HDV widget.
What's easier is to do the following...

1. Put the HDV Widget on your parameterized page and adjust the appearance as needed.
2. Link it to a single instance of the user-defined tag type that you're drawing on your parameterized page. (yes, I did just make a big assumption there.)
3. Now go back and open the HDV Widget's properties dialog. You'll have a tag option that wasn't there a moment ago.
4. Change that to use the page's parameter, as per usual. Which, I'm assuming, hands in that user-defined tag type.
5. In the HDV Widget properties you'll get a selection of child tags to include. Pick the tags you want to draw.

And done.

It's not a UDT but it's a Polling Driver and that made it work.

Didn't even flip out over Pump 3 not existing on 95% of the sites or the Flow Meters that are only connected at two sites.