I wish I had time to address this in more detail, but yes, although officials tried to prevent such mobility, there was sometimes movement between the status groups that were heavily discriminated against. In theory the Eta status was "baser" and therefore it would be less likely for someone from the Hinin group to voluntarily enter an Eta family, but people were not only motivated by considerations of status. See David Howell's book Geographies of Identity in Nineteenth-Century Japan and Maren Ehlers's book Give and Take: Poverty and the Status Order in Early Modern Japan for more details.