One thing I would say is that the baby should be treated on clinical symptoms, rather than on laboratory results, particularly when they are so weak that you have to do all this testing to show an abnormality in the Blood Bank.
A slight rise in bilirubin is normal in a newborn baby.
This situation is very similar to the difference between a haemolytic transfusion reaction, where, for example, there is a positive DAT, antibody can be eluted and there is a SIGNIFICANT rise in bilirubin and a SIGNIFICANT drop in Hb, and a serological transfusion reaction, where there may, or may not be, be a positive DAT, antibody may or may not be eluted from the red cells, a new antibody specificity may be detected in the plasma, but there is NO SIGNIFICANT rise in bilirubin and NO SIGNIFICANT drop in Hb. Your cases remind me strangely of the latter.