I believe there is a check for pregnancy when they first enter the bed, and also when they wake up/leave. No, I don't think they can join without marriage. I'm going to go back to the game soon so I'm happy to answer and additional questions but I really recommend joining the official Discord, linked on the store page, and then maybe you can send some screenshots and ask for detailed advice on how to get their needs up to where you require them :) Good luck, you'll get there!

Will workers join without marriage?

They died of old age. I was able to marry one of the children after unlocking the job board and getting a couple workers.
Now I am trying to get to a point to have children. Getting their rating up is proving difficult and I'm afraid they to are going to pass away before I can reach their needed rating before bed. They seem to have the rating needed when they wake... but, from what I have read, they need it at the point they get in bed.

If you don't have anyone available who's old enough and single, you may have to wait. It'll be a bit harder but keep in mind that all of the other start modes have you begin with only two adults at the most so it'll be a bit of a struggle at the beginning but it's very possible. Don't be afraid of restarting though, Clanfolk is about learning from your mistakes and trying again :)

I hope that helped.

@Drizzit How did they die? I haven't been able to play for a while because of IRL issues but IIRC the oldest one usually dies around the first Winter of old age. If they died of starvation or whatever, fix that issue first. Make sure you have someone hunt rabbits every day but more importantly set at least one eel trap and make sure it's set up as the tutorial tells you. You may need to increase the amount it fishes each day but make sure not to deplete the lake too much. If you need to build a second one try to find a large lake or a second lake.

Anyway, to get more people you need to research and build the Job Board which is unlocked by building the Vacancy Sign. If you don't have rooms to rent for visitors, just turn the Vacancy Sign off. When you have workers come to stay with you, once their happiness reaches 100% you can have them join by marrying someone in your Clan, if they're single.
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I need more clan members... the older ones died the first spring :(

do: put off important objects for a while, because gathering rocks is more important (I barely got by one of my first winters because i unlocked the oat soup, but knowing i couldve got the kitchen and kept more people alive)

lol Some surely are guilty of that Most are generally pretty friendly though ^^

Do: complain, complain, complain that anything that goes wrong is due to game being faulty and not your having done a possible error
Do: beg for symphaty for having problems instead of actually letting others give any helpful advice, throw tantrums when asked for any extra information on your game issues

Good suggestion! I'll add it!