Bridal Shower

No, you should never invite anyone to a shower that is not invited to the wedding.

No she definitely shouldn't be inviting people who aren't also invited to the wedding.

Do these people know they aren't invited to the wedding and are okay with it? Do you want them to even be there? Obviously, you know that it is impolite typically to invite people not invited to the wedding unless it is something like an office or church celebration where nobody expects to be invited but want to give you are gift anyways. This is something you should talk to your sister about. You are not obligated to invite them to the wedding if you don't want them to, but your sister has to communicate that to the people she is inviting. If you don't want them there period which it sounds like you don't, you should tell her that.

View Quoted Comment Yes they know they're not invited. It's a small wedding (55 guest). She knows who's invited since she's my MOH. I think I'll have a talk with her.

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I mean, if they are cool with not being invited, then that is fine. The biggest question is whether or not YOU want them there.

No. If they are not invited to the wedding, then it is a gift grab and a major faux pas. The only exception is when another group who knows and understands they are not invited chooses to host a shower for you because they want to celebrate with you, such as coworkers or church members.

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I think it varies by culture to culture, as long as everyone is cool with it and they want to come knowing that they won't be invited then it is fine IMHO. Also, it isn't gift grabby since she didn't invite them, her sister did. I assume these people want to come anyways and don't feel obligated to come

I mean, I was invited to a bridal shower I wasn't invited to the wedding for and I didn't mind

It's a faux pas to invite people to come celebrate something (especially with a gift) if they aren't invited to it.