APOGEE combined spectra of the analyzed stars in a narrow spectral window, covering the regions (gray shadow) around the CN features (top panel), Mg l lines (middle panel), and Al I lines (bottom panel) used to estimate N, Mg, and Al abundances. A quick comparison between the stars identified in this work and the APOGEE star (red line) with second-generation abundance patterns identified in a previous paper (Schiavon et al. 2017a) indicates that we would be able to detect very large N and Al enhancements. (Alonso-García et al. 2012).