Gaia XP spectra and best-fitting models for four MSMS binaries. In each panel, the black line represents the observed flux. The blue solid line shows the best-fit single-star model, while the orange dashed line represents the best-fit binary model. The pink dotted line corresponds to the primary component of the binary model, and the dark blue dotdash line shows the secondary component. For each system shown, the binary model is preferred as it achieves a lower χ² value than the single-star model. Top row: example NSS SB2 binary. Bottom row: example NSS astrometric binaries.