Color-magnitude diagram of Grus II (left panel) and Tucana IV (right panel). The star symbols indicate our FLAMES-GIRAFFE targets, larger symbols are the member stars determined in Sect. 4.1, and small black circles represent possible members from the catalog by Battaglia et al. (2022) based on Gaia eDR3 measurements. Numbers are the star IDs (Table E.2 and Table E.3). Figure A.1 also shows the CMD with isochrones of different metallicities overplotted.