Baby daddy making decisions on our baby????

Ladies,

Our daughter has cradle cap and his mother advised to put oil in her head and rub it off. We had both agreed that we didn’t want to apply any oil and just let the shampoo Bella Bee do the job on its own. Unfortunately, the dad just told me he went ahead and applied oil and scrubbed it off. I am very upset he went ahead and do this after we both agreed we didn’t want that. What are your thoughts? He said he did nothing wrong because he didn’t harm her. I’m upset the fact that he jumped over me and made the decision to do that. Thoughts?