If anything untoward was going on, is there anything you could do to intervene or would you just have to stand by and watch and leave nature to take its course (in spite of having 5 cameras)?
Does that answer your question?
Pretty much and of course I know there can be no intervention if there is a dust up.
If there is a dust-up (I like that), it will be over before we'd be able to do anything. And "over" meaning finished fighting, mostly they only last a few minutes and smart birds extricate themselves before they get hurt - the whole "live to fight another day" thing, that's a big part of an individual's and a species' survival hard-wiring.
As I said, we are just keeping an eye on two pairs that are both looking to nest close to one another.
From Princess' overall behaviour on the nestledge we don't see any real cause to worry about the nest, she's relaxed, napping and doing her thing. Ivy keeping an eye on the nestbox may be one-part Cowboy & Joli & the "other" pair in his territory, it could also be that that is "his" box - the one he hatched from and the only site he has ever nested at/in/on. And of all our birds, Ivy is the only one who willingly goes all the way inside the box - when it rains hard, he hangs out inside with the kids, Princess never goes inside the box unless she has to cover the eggs/chicks. In fact, Princess lays her eggs half-in/half-out. Madame always nested on the outside, Maud was like Princess, half-in, half-out and Madame and Maud had a smaller box.
It was a quiet day - Princess and Ivy traded a couple of times, were calm and quiet and napping on the eggs in the rain. Ivy hung out on the nestbox for a couple of hours but he too was relaxed, one foot up and cat-napping for much of the time. That is very normal peregrine at the nestsite behaviour.