This study is for children with severe blood cancers or solid tumors. It explores using a special kind of stem cell transplant from a family donor who is a partial match. The treatment involves removing certain cells (TCRαβ+ and CD19+) from the donor's cells to make them safer. After the transplant, the drug Zoledronate is given to help the immune system.

Conditioning Regimens: Before the transplant, patients receive different medicines and radiation to prepare their bodies. Patients with severe leukemia get strong medicines and radiation, while others get a milder treatment.

Transplant and Medication: After preparation, patients get the stem cell transplant. If needed, extra cells can be added. Some patients receive medicines like mycophenolate mofetil and tacrolimus to prevent complications called GVHD. Zoledronate is given to help the body accept the new cells.

• Participants need follow-up visits after the transplant.
• Study includes five doses of Zoledronate, given every 28 days after transplant.
• Eligibility requires having a family donor and meeting health criteria.