Of the two sons, Arnt and Bartholomäus, who helped the elder Barthel Bruyn in the painting of the Carmelite cloister in Cologne beginning in 1547 and subsequently practised their father's trade, only one appears to have enjoyed success. Whereas the first-born, Arnt, died in 1577 heavily in debt, and from whom no major commissions are recorded, the younger Barthel took over from his father both artistically and materially. In 1550 he married the well-to-do Agnes Patberg (died 1623) from Werden, in whose name he sold inherited properties in Werden. In 1557 Barthel Bruyn the Younger became the sole owner of his father's houses and atelier; he must have bought out his siblings. He served as a councillor beginning in 1579. The patrician Hermann von Weinsberg, one of his clients, tells of the painter's complaining of declining vision; it is possible that he was no longer able to paint very much after 1590. In 1593 he and his wife drew up a joint will. He died highly regarded and wealthy.
From our present-day perspective, this is somewhat surprising in view of the fact that the work of the younger Bruyn is lacking in any sort of innovation. The son closely adhered to the stock of compositions and types inherited from his father; except for updating costumes, he only occasionally modernised his use of line to satisfy contemporary tastes, but without improving the effect of his paintings. As a rule, his flesh tones and his colouring as a whole are paler than those of his father. Since the younger Bruyn never developed a truly individual style and almost never signed his works, scholars have naturally had a difficult time isolating his oeuvre. Yet two assured works permit an identification: the portrait diptych of abbot Petrus Ulner in the Rheinisches Landesmuseum in Bonn, certified by an inscription on the frame and dated 1560, and a triptych for Hermann von Weinsberg in Cologne's Historisches Museum for which the commission is documented.