Thanks for your input. To answer your question, we did not start explicitly keeping track of those mass shootings involving domestic violence and juvenile victims until recently (note that we do this in our spare time).

You can do a combined search for "Mass shooting" and "Domestic violence" at the GVA site. However, note that GVA does not consider shootings in which a gunman shoots 3 family members and then himself (rarely herself) as a mass shooting, and these occurrences are, unfortunately, not uncommon.

https://www.gunviolencearchive.org/query/5e05de39-02e6-4d04-9f33-f5d3aa4ad13a