Electronic textile (e-textile) systems require reliable interfaces between materials with dissimilar mechanical properties, as they contain a combination of rigid and flexible or stretchable parts. For example, textile sensors, such as those knit or woven from conductive fibers, or printed onto textiles with conductive inks, often need to be connected to rigid electronic components. Rather than directly attaching rigid components to textile substrates, interposers—devices that route between different types of contact, or components with mismatched pitch—can be used. We demonstrate two variations on an interposer for connecting stitched conductive tracks on textiles to flexible PCBs, using two types of connectors not previously used in e-textiles. This format enables modular design, where an e-textile system is constructed from discrete parts which can be easily removed and replaced, for repair, updating, or recycling. In this letter, interposer prototypes were subjected to preliminary mechanical and electrical testing, showing good resistance to repeated bending and twisting.