Pre-main sequence clusters are excellent laboratories for studying dynamical interactions. Examples are the nearby eta Cha and epsilon Cha clusters,; sparse, compact, 5-10 Myr-old systems deficient by a factor of 2 in low-mass stars and brown dwarfs. Sensitive searches have completed the core population and found no members in the immediate field, to 2-3 times the core radius. The latest photometric and proper motion catalogues have sufficient precision to reliably detect members distant from the core. The observational constraints are severe; candidate members must be photometrical consistent with core members, have Li and other spectral indicators consistent with the cluster age, and have space velocities consistent with ejection early in the clusters life. In the case of eta Cha, candidates members have now been detected up to 5.5 deg spatial separation from the cluster core.