Pheromone spray is just (synthetic?) cat hormones, the type they leave on you when they rub their face on you. So I would presume it’s safe as long as toddle doesn’t ingest it. There is also an herbal calming formula by Nature’s Miracle that amazon has as an add on item for $3 right now. Going to try that for my easily stressed girl who has urinary crystals/frequent and blood tinged urine but doesn’t pee outside her box. She just stops eating or drinking for a week at a time if you bring her to the vet or try to change her food to the prescription diet to help the crystals.
She seems super chill otherwise unless I consider that she took over two months to be okay with our other cats. I’m thinking of asking the vet for some Prozac for her.
Ask around locally. I think a lot depends on your area and the specific rescue. Here I think they would be pretty understanding if a pet just can’t handle children in the home. Where I grew up, they would probably be pretty snotty about it.