HST images of all PNe in this paper, in linear scale (a nonlinear stretch is shown in Fig. A.2). DdDm-1 was taken in the F675W broadband filter including the Hα line. Contrary to the other panels shown here, this image of DdDm-1 suffers from spherical aberration prior to the installation of HST’s corrective optics. F502N refers to a narrow-band filter including the [O III] line. These images include the emission from the central star. [O III] refers to that emission line extracted from a slitless spectrum. The spectral resolution is too low to resolve the intrinsic line width, hence these can be considered 2D line images, without the central star whose continuum is dispersed along the horizontal axis. The white circle shows the NISP-S EE80 disk with a radius of 0.″5. The field of view is 2″ × 2″.