Small birds are difficult to photograph: they are agile; fast; have an agenda which does not include you; they run away. So you carry bait with you: a pocket of mealworms works well.
Small children have very similar characteristics. But parents object to them being fed mealworms. So same tactics, different bait: children like puddles – it’s a fact.
And just set up the environment…
You can even get them into someone else’s fashion shoot… (apologies to the fashion photographer in Millennium Square)
And the concentration on splashing completely hides the photographer.
And if it’s warm enough, just hose them down.