In my opinion, this very much depends upon the underlying pathology. For example, if the patient has an auto-immune haemolytic anaemia, the chances are very strong that the DAT will be positive before as well as after the transfusion, and that any eluate will be positive with all red cells tested (of normal type). The chances of detecting a new antibody specificity on the DAT positive red cells under these circumstances is disappearingly small.
Therefore, if the sample is sent to a reference laboratory on a regular basis, your manager will be 1) showing a degree of ignorance that should