Paradigms of bilinear maps β : E 1 × E 2 → F between locally convex spaces (like evaluation or composition) are not continuous, but merely hypocontinuous. We describe situations where, nonetheless, compositions of β with Keller C n c -maps (on suitable domains) are C n c . Our main applications concern holomorphic families of operators, and the foundations of locally convex Poisson vector spaces.Classification: 26E15, 26E20 (primary); 17B63, 22E65, 46A32, 46G20, 46T25 (secondary).