Posterior distributions of the C/O (left), carbon ¹²C/¹³C isotope (middle), and oxygen ¹⁶O/¹⁸O isotope ratio (right) for J0835, J0501, and J0500. The ¹²C/¹³C values for the Solar System (terrestrial value) and ISM are 89.3 ± 0.2 (Meija et al. 2016) and 68 ± 16 (Milam et al. 2005), respectively. The C/O value for our Sun is 0.59 ± 0.08 (Asplund et al. 2021). The ¹⁶O/¹⁸O values for the Solar System and ISM are 557 ± 30 (Wilson 1999) and 525 ± 21 (Lyons et al. 2018). The purple error bars represent the young BDs observed and analysed by González Picos et al. (2024, P₁: J1200, P₂: TWA28 and P₃: J0856), the orange error bar DENIS J0255 (R₁) by de Regt et al. (2024), and the yellow 2M0355 (Z₁) by Zhang et al. (2022).