I also agree that it's situation dependent, which is not among the choices. What kind of starship are we talking about? A purely exploration vessel or one that has a good likelihood of seeing combat? The Enterprise D proved to be a very risky place for families, based on the episodes we've seen.
The problem with this is that it isn't just combat. The Trek universe has shown us that any ship wandering out in the great unknown is in almost as much danger from random anomalies or previously unknown crazy lifeforms as from a more traditional "combat situation", i.e. hostile spacecraft. As Q said, exploring the galaxy isn't for the timid.
I think any ship that has a greater than 25% chance of seeing combat should NOT have families, and those less than 25% have them conditionally. Meaning that families need to be heavily screened. They may be there for officers and others who accept the risks, but overall they must be a small minority of the population.
This is along the lines of how I've always viewed it. Ron Moore has a quote where he talks about how "awkward" it was to see Picard ordering red alert and all hands to battle stations as the ship faces down a Romulan Warbird while we know there are kiddies running around underfoot, and I agree. He called the families on the ship thing a "failed experiment." I presume he means from a production standpoint, that it was an idea the creators had that ultimately proved to not be so great, but I look at it as a "failed experiment" in-universe, as well. Starfleet had this idea, perhaps borne of overconfidence in their peace-keeping abilities after nearly a century of peace with the Klingons and their only major conflict being against the comparatively wimpy Cardassians. But the results of this "experiment" were clearly disastrous, so they scrapped it later.
I can see a screening process being adopted, along the lines of what you suggest. Individual civilians could apply for residency on a ship; this would allow for your bartenders, scientific specialists, and officers' loved ones. But the screening would include a battery of tests to make sure the person would be able to either contribute, or - at the very least - stay out of the way during a crisis (and a bunch of waivers they'd have to sign as well, no doubt!). Instead of "chance of combat", I think danger would be considered in terms of "distance from Federation core worlds." It seems to me that the farther away from
those you are, the more dangerous things become - whether that danger is from hostile vessels or anomalies-of-the-week. Within the Federation, there are more areas that have long been fully charted, and any hazards catalogued, so a ship whose assignment keeps it on patrol within a UFP sector is far less likely to run into trouble unexpectedly than a ship out exploring unknown, uncharted space (or a ship that spends its time hanging out along the border with a hostile power). The higher the "danger rating", the more difficult it is to obtain permission to live on that ship as a civ.
And no children, period, except on the safest of the safe (ships with static assignments that rarely stray out of rock-throwing distance from a starbase).
It's funny, when we watch TNG and see those children/family episodes and there's no battle scenario, it's easy to accept their presence. But when you have these episodes sending the Enterprise into battle or facing extremely dangerous situations, there's not a single sign of children or families. It's easy to forget that they are there. One exception I can think of was in "Generations", when we see our hero characters carrying kids to safety in the primary hull. But what about "Masks", where so much of the ship turned into an Aztec nightmare? No sign of children. And what about the mutations in Genesis? We have to believe that all the kids on board were transformed, but we never saw them. Completely out of mind.
I never really thought about it this way, but you're right. They did highlight it a couple of times, though, most notably in "Rascals." Granted, it may have seemed worse by virtue of the entire episode being terrible, but Riker's "our families are a strength" line during the scene with the Ferengi threatening to start executing children really put an uncomfortable spotlight on the whole thing.
One thing I always thought the Enterprise should have is a special large cargo ship incorporated into the hull structure that would serve as a massive life boat. When the Enterprise is about to embark on a potentially hostile mission, Picard would order all the families (save the essential crew members) into the life boat and have them orbit some benign world while the Enterprise is off taking risks.
I agree with
DonIago: what you're describing is basically the saucer section. How it was used in GEN is exactly how I always felt it should be used. The idea that the ship became
more combat-effective by having half of the thing shear off and fly away always struck me as extremely silly, and having saucer separation be a standard maneuver when combat was expected was a really terrible idea that I'm glad they did away with.