“How can we let one kid do something that is hurting the other one?” Sorry but YTA. That’s exactly what you’re doing, I know you’re trying to avoid your youngest sons upset, but in the process you’re hurting your daughter.

Who cares if they’re related by blood, your daughter said it’s one of the only things that makes her happy every month. They’re “aunt” is right, if she doesn’t feel equipped to handle what is required when watching your son I don’t think you should force that. Hear what she is saying and try not to take it personally.

Your son is your responsibility, and taking this away from your daughter to stop his tantrums is enabling that behavior. I’m sorry that you’re frustrated, I’m sure this has been confusing and hard on you and your wife. I’m glad you guys are taking steps toward his diagnosis and helping him. I hope it works out for you and your family, and you continue to let your daughter have that special time with her aunt.