Union SG U18: every transfer in and out, fees paid and earned, squad market value.
| Date | Player | From | To | Fee |
|---|---|---|---|---|
| 2025-03-21 | Giorgi Kavlashvili | Union SG U18 | Union SG | — |
| 2024-07-01 | Giorgi Kavlashvili | Westerlo U18 | Union SG U18 | Free |
| 2023-07-01 | Noa Louche | Union SG U18 | Union SG U23 | — |
| 2023-07-01 | Daniel Tshilanda Kabongo | Union SG U18 | Union SG U23 | — |
| 2022-07-01 | Nathan Huygevelde | Union SG U18 | Union SG U23 | — |
| 2022-07-01 | Mohamed Asri | Union SG U18 | Union SG U23 | — |
| 2022-07-01 | Daniel Tshilanda Kabongo | Union SG Yth. | Union SG U18 | — |
| 2021-08-21 | Rodolfo Lippo | Union SG U18 | Without Club | — |
| 2021-07-01 | Nathan Huygevelde | Union SG Yth. | Union SG U18 | — |
| 2020-07-07 | Rodolfo Lippo | Unknown | Union SG U18 | — |