Cover Scents Application

I need some help with cover scents.

1. Is it safe to spray an alcohol cover scent over an oil, silicone, or alcohol based Pheromone?
2. Is it safe to apply an oil based cover scent (like The Fragrance Shop) over an oil, silicone, or alcohol based Pheromone?
3. Is it better to apply the pheromone or cover scent last?
4. Are alcohol or oil based cover scents better in regards to pheromone usage?

Thanks in advance......