impact of separation on Austrian visa status

Your sister may well need both an immigration lawyer and a family law lawyer. International child abduction happens, and the recourse available depends on which international treaties/conventions the jurisdictions involved have committed themselves to (plus what their actual track record of cooperating is). The best possible help you could get from metafilter would be a lawyer recommendation (though even that might be harder without knowing the country of origin). Next bet would be a helpful website. Any specific information anyone tries to give you, without even knowing the country of origin involved, could be more trouble than help. This is too serious for her not to get legal help right away. You don't need to wait for a dispute to speak with a lawyer. It's better if you don't. The most helpful thing you can do for your sister now is to push her as hard as you can to consult with an actual legal authority, and send her the money if she needs it.

Definitely, definitely, definitely have her talk to her embassy. That's exactly where she needs to go, like, Monday morning.

There is important info missing - it makes a difference what type of visa they have and how long they reside in Austria. She will only get real help from a lawyer who is familiar with her circumstances and Austrian family and immigration law. It all depends on the particular case: from my understanding, a dependant's visa is not automatically revoked after a divorce. However, the dependant has to fulfill certain criteria (income/healthcare/language proficiency/own apartment) to be eligible to stay in Austria if the divorce happens within the first 5 years of their stay in Austria. But since the visa has been renewed for another 5 years it would seem that they live in Austria for quite some while already, and would point to visa type Daueraufenthalt EG -- which is a game changer. Basically whatever she has, he has and the longer the stay the more grounds he has to independently seek right to stay. Do they live for more than 8 years in Austria? The Daueraufenthalt EG (for the dependant they add Familienangehöriger) grants unlimited settlement with unrestricted access to the labor market - the permit itself is valid for 5 years and needs to be renewed but it does not change the fact that the person's right of residence is unlimited. It is a pitty that you posted anonymously. To really be able to help more info is necessary. A few more thoughts though: Help your sister understand that there are different issues at play here. She needs to take care of her divorce (mind you there are apparently different kinds of divorce -- establishment of guilt) and seek sole custody. She needs to take precautions so the daughter’s whereabouts are stable and uninterrupted. Inform the embassy and the school about the issue. (I am saying this based on the picture you painted, "his anger issues", "take their daughter out of country" - obviously an amicable solution where both parents remain happy and present for the child is always favorable. Your sister/you obviously know the situation - act accordingly). She needs to inform the Aufenthaltsbehörde within a month of the divorce about the fact of the divorce. If the husband's visa is not the Daueraufenthalt EG they will inform him about the further procedures. An informal separation where she provides financial support for her husband seems like a bad idea - this way the husband retains all and every right he currently has. At this point she needs to look out for her and her daughter's best interest. This is a http://www.migrant.at/, although the women there focus on employment and residency, they might point your sister in the right direction or recommend a lawyer. http://www.familienberatung.gv.at/beratungsstellen/?user_familienberatung%5Bstate_select%5D=&nearbySearch=0&user_familienberatung%5Bfocus%5D%5B23%5D=1&user_familienberatung%5Blanguage%5D=1&user_familienberatung%5Bsort%5D=1&topic_submit=Suchen#Wien_1010 (gov. department sponsored / you call anonymously) that might provide some help. Depending on who your sister's employer is, they might have some type of counselor/advisor/other resource that would be helpful to her in this situation. IANAL - answered to the best of my ability, laws/regulations are always subject to change. Good luck.

Please encourage her to move her daughter's passport to the safest possible place, well outside the home, as soon as possible, just as a precaution while awaiting the expert counsel suggested above. She needs a lawyer immediately, and should not enter into any discussions with her husband about the financial support that she intends to provide or any travel plans. If you can, please tell a mod what their country of origin is. Your question seems sufficiently anonymous and it will allow people to point you to more specific resources/information. Sending good wishes to you and your family.