I merged two lists I already had created in NXT today, only to discover that I couldn't THEN filter them by head of household. It has to be done in the initial lists, which makes no sense to me at all. If any constituents are added manually to a list as part of a merge, they are then exempt from this particular filter, which makes me wonder how many other filters applied to merged lists aren't working the way I think they should be working. I want to be able to work in NXT lists, because they are easier to use in a lot of ways, but in order to avoid duplicating the work I had already done, I ended up saving the list to database view and just using an export I already have set up to apply the HoH filter.