When I take over a new settlement, I will build just enough beds/defense/water/food to make the "up arrow" appear next to "happiness"...and then shoot all the settlers in the head.
I then store all the food/water/defenses/beds...just in case I later wish to build something there.
The only settlement that this doesn't seem to work for is that one with the child settler (damned poilitical corrrectness), and some "named" ones.
This really makes it easy to keep track of "working" settlements, but you can still do the MM quests where Preston asks you to open new ones.
Anybody else having homicidal actions due to the settlement system?
Love to build...hate the defense limitations. (Defenses should work even if we are too busy to came and watch the fireworks.)