The only way she is your sister-in-law is if she is directly related to the person married to you(or legally related)
If you father has surviving spouse or/and children his sister would generally not be considered an heir in most states if your father died without a will. You can check the laws of intestacy for your state at the related question link provided below. If his sister inherited under the terms of his will then she would be considered an heir.
Your sister's daughter would be considered your niece.
No. If you mimic your sister or if you imitate or act like her, you would be impersonating her.
That would be considered incest and is very wrong. the answer is, YOU DON'T!
Yes, she would be considered a natural heir.
Of course she is otherwise they wouldn't be sisters they would be half sisters or something like that man you're stupid
They have the same mother but not the same father. *Technically she would be considered the "Half" sister, because your supposed to have the exact same parents to be considered "Full" blood. However it is what it is and she is a Clark!
If your sister in law is your wife's sister then she would be nothing to your sister. However if your sister in law is your brother's wife then she would also be your sister's sister in law.
Your brother's wife's brother is your brother's brother-in-law and your sister-in-law's brother. But he is not considered to be related to you. Usually you could just refer to him by his name.
Yes sibling by blood would count as that as long as you have contact or live together.
No. Your husband's brother-in-law would be your brother or the husband of your husband's sister. Your sister is your husband's sister-in-law. Your sister's husband is your brother-in-law but the English language has no term to describe a relationship between your husband and your sister's husband. In everyday English usage, however, your sister's husband is referred to as your husband's brother-in-law, yes. But it isn't exactly correct.
Yes, I suppose that they would be sister-in-laws. Because your sister is your husband's sister-in-law, and the other sister is his sibling, then I suppose they would be sister-in-laws.