If our mother and father already died no will and the house was under our sister’s name, what are the rights of the other siblings?

If your parents dare both dead and neither had a Will then the assets of the last to die are distributed to all of their children in equal shares through a probate of the estate of the last to die. If they transferred their house to your sister before they died then the house is not in the estate and is entirely owned by the sister. You should obtain a copy of the deed from the office of the county recorder of deeds and have an attorney look at the deed that purports to transfer the house to determine if it is proper and the nature of the transfer. If the transfer was as a tenant in common there may be a portion of the ownership interest that remains in the estate. If the deed was never recorded then the transfer may not have actually occurred. Your situation should be reviewed by an attorney to determine your options.

If the house was in your sister's name, it is her house. Sorry, unless you can prove undue influence or lack of capacity, you won't be able to do anything about it. Proof of this would be very difficult if you were to try this method.

If the house is in the sister's name, it would appear to be hers. How did it come to be in her name? It may be subject to attack.