Creat a layer on every slide automatically

Folks,

I've searched around this forum but can't seem to find out how to:

Add a layer on each slide automatically. I figured it might be as simple as adding the layer with the graphics and triggers to the Slide Master, but this does nothing.

I added a layer and triggers to the slide master but it seems the Master is only used for colours and graphics and not layers and triggers. Am I correct in this or am I missing something.

I have a couple of error layers that I'd like to have triggered when a learner clicks "next" but the timeline is not complete. Thus far I have been adding each layer and trigger manually, PITA and time consuming. It also is prone to errors because it is a step that has to be created over and over, this adds to the time to fix bugs.

Any assistance is appreciated. If this is not a function then might I suggest it. It would seem logical and plausible using the Slide Master.

Thanks in advance for any assistance you can offer, I'm a newby to Storyline and e-course creation.