Blood transfusions in 1 year old

Has anyone Here gone through a blood transfusion for their kid? My SIL texted me today saying her baby’s doctor called her saying that her baby needed a blood transfusion asap because his iron was at level 4, that it could also be cancer. Will the baby need rest after a transfusion? His birthday party was scheduled for tomorrow too…. Is there a way I can help her as in with her other kids or will her baby be okay right away? She hasn’t updated me yet. TIA.