How to kick out a mooching family member?

[Amalthea]

Well, honestly, if your dad was so successful at it previously, why not ask him to do it again?
Aunt probably sees him as a bad guy already. This keeps Mom and Grandma in the clear and you and your brother out of it completely.

Naked Thanksgiving is a great idea, but it may just backfire.

Because what he did was go around the house naked until she left.  That is how the idea of Naked Thanksgiving was born.

[Shopaholic]

Well, honestly, if your dad was so successful at it previously, why not ask him to do it again?
Aunt probably sees him as a bad guy already. This keeps Mom and Grandma in the clear and you and your brother out of it completely.

Naked Thanksgiving is a great idea, but it may just backfire.

Because what he did was go around the house naked until she left.  That is how the idea of Naked Thanksgiving was born.

I'm sorry I don't have any good advice, but that totally made my morning .

[cicero]

She has not actually done anything illegal, so I think any legal entity would require us to ask her to leave before they would further assist.  As no one has actually tried the polite spine approach because it feels mean, I would at least like to try it first.  If it fails, we'll go from there.  If my mother has to be the one to do it, she would benefit from something of a script to follow and assurance that kicking her sister out doesn't make her Queen of the Female Dogs as much or more than I would.

I *doubt* that using a polite spine approach would help now, and i really think you are beyond "polite" at this point, but if you want to try this first then go for it -

the important thing is to present a united front to your aunt - you *all* need to be on the same page, and you can't back down. I think your mom has to be the one to talk, but you should all be there supporting her (in person or on skype).

she should say something like:

"Sister, you have been here for X months. before that you were at my home for Y months. during this time I have spent $$$ on you and mom has spent $$$ on you. We cannot do this any more. THe other issue is that mom now needs help to recover from her surgery - she is unable to recover with you around. TOday is November 11th. I want you to start packing your things, look for other housing, and be out of here by November 30. "

[Tiamet]

While I accept you don't want to make this a legal issue, I strongly suspect this may become one.

What are you going to do if your aunt flatly refuses to leave?  As PPs have said, you and your brother (and in fact, your mother and father) don't own the house.  If I lived somewhere and relatives of the owner told me to get out, I'd ignore them.

I honestly think this goes beyond etiquette - you seem to be trying to find out how to politely evict a completely unreasonable person without the owner of the house getting involved and I don't believe that is possible.

[YummyMummy66]

Honestly, your family has let your Aunt establish her residence in her mother's house.  This could very well be a legal issue.

I think that before you do or say anything, have your ducks in a row and speak to an elder attorney or someone knowledgeable in the laws regarding this.

This way, when Aunt comes back to you says, X, Y, Z, you will already have an answer to her replies and you can state so with conviction and knowledge on those answers that you give, stating that you have already consulted with an attorney.

This will make her see that your family is truly serious about her being out of the home.

[Amalthea]

I asked for etiquette advice because this is an etiquette forum.  If I need legal advice when the etiquette fails, I'll go somewhere where it isn't against the forum rules.