Parent's in Law

This is your FMIL you're talking about so I would approach the issue with some respect. If you truly think she might start drama, then perhaps your FH should address this with her. I doubt giving her a set of "rules" would result in less drama but instead would fuel whatever angst she has towards you.

He needs to be standing up for you so if he’s not the one telling her that her behavior needs to stop, then there’s an issue. If he agrees that her behavior is unacceptable, he should let her know that if it happens at your wedding, she’ll be asked to leave. But this goes beyond the wedding. He should also be telling her that you’re his (future) wife and if her behavior continues period, then he’ll be reevaluating his relationship with her.

If there were a specific thing (e.g., she's an alcoholic, and you don't want her getting falling down drunk), you might be able to do it. But bad mouthing or drama is pretty vague. I think you just have to deal with it if the situation arises. And even then, he (not you) should be the one to talk to her. That way, she has to deal with her own son, and it's less likely to make your future relationship even worse.

I agree with the others, it's not you that should be addressing this, it's your FH that needs to talk to her.

Setting "rules" beforehand might backfire on you. I'm a pretty nice person and if someone came up on me and said I better act a certain way or I would have to leave, I would be pretty tempted to test them on it. More than just focusing on the behavior at the wedding, your FH and her probably need to work something out about coexisting anyway. You all don't have to like each other, but ideally you respect each other and your respective relationships.

Seriously? It's her son's wedding. What are you worried she's going to do?

IMPO, you shouldn't be discussing this with her. He should discuss this with her and his father.

Girl I understand you completely. My FMIL has already thrown a fit at SO many things (ex. having beer/wine at the wedding instead of a dry wedding, not having FFIL as the BM, she thinks my dress is trampy because it is a v-neck... too much to deal with). Honestly I would make sure your FH handles her. It will come a lot better from him and she will know it is serious. The more it comes from you and not him, the more she will try to prove she can do whatever bc you are marrying her little boy.

No, you can't make "rules" for your future in-law. If you're doing your wedding day right, you won't even notice she's there, no matter what she does.

She's about to be your family. If you impose rules on her or attempt to make her leave, you're going to have much bigger problems than having your day ruined. Where is your fiance in all of this?

This sounds as though is already bad blood between you and her; it also sounds like you are trying to control what she ways and does at your wedding.

Relax, stay calm and take the higher road. If she is all out drunk, your hubby/his family can deal with her. DO NOT approach her with a laundry list of things she can and can't do - it will end very poorly. If there is something bigger, it is the role of your fiance to speak to her.

It might just be me, but asking her to leave her own house might be a bit too bold. If you are that worried I would just look for somewhere else to have the wedding. Also if you don't get along with her and you do have the wedding there it can go one of two ways 1 she he's it over you forever that without her you wouldn't have had a wedding.
2 you feel beholden to her or feel very pressured to perform for her.

I miss read the post... feeling dumb but don't know how to hide it. Sorry.

My MIL has a tendency to cause problems. She very dramatically did not show up to my bridal shower which she helped pay for. So I partly understand what you are feeling... however, we get along because no matter what she says or does, she is my husband's mother and she deserves my respect. Our lives will be better if I don't increase the divide in his family. I also know he will always have my back if needed.

That being said there were some issues during our wedding day and she tried to cause a scene. However, we had already discussed what we thought may happen (we were wrong, but it allowed us to prepare how we would handle issues). My focus was on my new husband and being in the moment during our wedding. It affected him more, which I feel badly about, but it's easier for me to move beyond her issues than it is for him because she is not my mom.

Point is we knew that she was likely to be dramatic and she was. We did not try to set "rules" for her to follow because that is ridiculous since she is an adult. We prepared ourselves for how we would handle it and knew that any dramatics would reflect poorly on her and not affect the fact that we are getting married.

I have no advice that hasn't already been said, but I'm so sorry you have to deal with this. I get along with my FH's family so well and it makes me sad when I see things like this. I'm hoping she can pull it together and just let you two be happy, but I know that's a long shot. Best of luck!