Sylgja (the Shor Stone miner) is marry-able anyway. You do not need a code for her.

She does not have any dialogue appear for marriage when I talk to her. Why is the code not working?

You forgot to click on her when you have the console open. When you click on her you should see (insert ID here).

Are you wearing an amulet of Mara?

Can buy one in the Temple in Riften.

ok it worked for Anneke but not for Sylgja. Is the 19809 number different for Sylgja?

Are there any disadvantages to force marrying someone over normal marriage? Can you marry more than one person? Can you remarry after she has died? Can you change your wife's clothes?

Falls under "TMI" maybe.

Sylgja is marriageable anyway, so you don't need to enter any codes. You just have to talk to her and do her quest and then you should be able to marry her. The code doesn't work because she is already a member of the faction you are trying to add her to.

Forced marriage usually works just like normal marriage. Sometimes it can have weird side effects, though, so it's always a good idea to keep a save from before you did that.

You cannot remarry after your current spouse dies without other console commands, which I don't know yet, since I always leave my spouse at home anyway. There are probably ways to get them to change clothes, but I've never bothered with that.

You have to do Sylgja's quest to get her to marry you.

What kind of weird side effects?

I did. Whenever I tried talking to her, she says something like, "You again. Every time I see you, my blood boils." She's mad at me for some reason. Am I unable to marry her now?

The most common ones appear to be them not opening a shop, or losing the training option if they previously had it. But, I am aware of one person who is marriageable without console trickery who is a trainer and a shopkeeper and still often bugs after you marry him, so whatever causes these bugs isn't restricted to people you've forced to marry you, anyway.

She's mad because you killed her father... You have to either reload, or do the setrelationshiprank thing.

I find it odd that Anekke is willing to marry her even though I killed her husband, but Sylgja refuses to marry me because I killed her father (same guy). Oh well.

What is the setrelationship prank?

Also, is there any way to have more than one wife?

I think it's "player.setrelationshiprank 4" (after clicking on someone) to get them to like you enough to marry you.

And no, you only get one wife. Apparently if you propose to more than one person, they'll all show up at the wedding and be mightily ticked off at you.

If your current wife dies, can you have a new wife?

Nope. There's probably a console command for that, though. I've just never had the need to look it up.