RecruitingDevice studyαβT Cell/CD19+ B Cell Depletion for Alternative Donor Allogeneic Hematopoietic Cell Transplantation (HSCT)This is a study utilizing the Magnetic-activated cell sorting (CliniMACS®) Alpha-Beta T-cell (αβT)/Cluster of Differentiation 19 (CD19), also called B lymphocyte antigen CD19 depletion device for Children and Young Adults with Hematologic Malignancies undergoing alternative Donor Allogeneic Hematopoietic Cell Transplantation (HSCT). Patients will receive an allogenic HSCT from a matched unrelated donor (MUD), mismatch unrelated donor (MMUD) or a mismatched related (haploidentical) donor. Patients will receive a granulocyte-colony stimulating factor (G-CSF) ± Plerixafor donor mobilized peripheral stem cell donor transplant following CliniMACS® αβT cell/CD19+B cell depletion. Cluster of Differentiation 34 (CD34) and αβT cell content of the graft is determined based on the transplant indication.