It is inevitable that, at some stage, a worker and a carer are going to disagree on a course of action. On the agency side will be due process, accepted procedure - both pushed with varying degrees of enthusiasm depending on the agency, as well as experience and expertise. Depending on how long the placement has been, on the carer side will be knowledge of the child, experience, and quite possibly some degree of affection for the small person.
So what do you do when you, as the carer, don't agree with what's proposed? How hard can you push back?