I would like enter all information into the parent that make sense. I would enter the earliest production year, the country of origin if it is equal for all children, the DVD production studio, the subset of genres which are common for all children, the highest rating, the sum of all run times, the common subset of region codes, the common subset of audio tracks, the common subset of subtitles, the superset of all features, the video format if equal for all children, the concatenation of all overviews and the common cast and crew.

I have said I would like because the current rules prohibit some of those things explicitly while the rest is allowed.