CD45RA-depleted CD19-CAR T Cell Consolidation After TCRαβ+/CD19 B Cell-depleted Haploidentical Hematopoietic Cell Transplantation for Relapsed/Refractory CD19+ ALL and Lymphoma

The purpose of this study is to learn more about newer methods of transplanting blood cells donated by a partially matched family member to children with high-risk CD19 positive leukemia ALL. Primary Objective: \- To assess the safety and feasibility of combining CD19-CAR(Mem) T cells after TCRαβ+/CD19 depleted haploidentical donor transplantation for pediatric patients with relapsed/refractory CD19+ B-cell malignancies. Secondary Objectives: * To estimate 1-year post-transplant overall survival, event-free survival, and GVHD-free relapse-free survival (GRFS). * To estimate cumulative incidence of engraftment, acute and chronic GVHD, and immune-related adverse events, including CRS and ICANS.