Forced alignment, a technique for aligning segment-level annotations with audio recordings, is a valuable tool for phonetic analysis. While forced alignment has great promise for phonetic fieldwork and language documentation, training a functional, custom forced alignment model requires at least several hours of accurately transcribed audio in the target language—something which is not always available in language documentation contexts. We explore a technique for model training which sidesteps this limitation by pooling smaller quantities of data from genetically-related languages to train a forced aligner. Using data from two Mayan languages, we show that this technique produces an effective forced alignment system even with relatively small amounts of data. We also discuss factors which affect the accuracy of training on mixed data sets of this type, and provide some recommendations about how to balance data from pooled languages.