Is it unlawful for one who adorns veiled brides (with a veil and makeup) to do so, knowing that the wedding is mixed?

The permissibility of cosmetic work for women revolves around its purpose and type. It is permissible if it is for the husband and free from forbidden acts (such as plucking eyebrows, hair extensions, and exposing 'awrah), and provided she does not display her adornment to non-mahram (definition) men. However, if any of these conditions are not met, then the cosmetic work is not permissible because it constitutes aiding in a forbidden act. Similarly, it is not permissible to apply makeup to veiled women if they will go out with that adornment and be seen by non-mahram men, because it constitutes aiding in a sin.