Measure-valued Pólya urn processes (MVPP) are Markov chains with an additive structure that serve as extension of the generalized k-color model towards a continuum possible colors. We prove that, for any MVPP (μn)n≥0 on Polish space X, normalized sequence (μn/μn(X))n≥0 agrees marginal predictive distributions some random process (Xn)n≥1. Moreover, μn=μn−1+RXn, n≥1, where x↦Rx is transition kern...