your grand niece or nephew in-law (-Kasadie)
My son's wife has a niece... how is her niece related to me?
Let's see . . . the natural daughter's stepfather would be the husband of the decedent. He would be the surviving spouse. Generally, the surviving spouse of someone who dies intestate (without a will) is the primary heir. Each state has its own laws of intestacy and they vary from state-to-state. You would need to check your state laws to determine your status as an heir-at-law. You can check your state law at the related question link below.
(in the US) it would depend on the laws of your local jurisdiction AND what the relationship of the seven people were to one another.
Yes, in Massachusetts the age of consent is 16, so a relationship between an 18 year old and a 16 year old is legal. However, there are laws that criminalize sexual activities with minors under 16, so it is important to be aware of the specific age of consent laws in the state.
Palimony is when you have lived with someone for many years and are no longer with them and sue for rights from the relationship. Florida does NOT have common law or palimony laws. You are out of luck if you live in Florida and have considered yourself married. You are not married nor it is recognized by the state.
This is covered by state intestacy laws - absent a will, the wife will inherit.
In the United States there are no "legal relationship" between relatives, because no laws define these relationship. These are all customary terms. The child of one's niece or nephew is one's great niece (if a girl) or great nephew (if a boy). The elder relative is a great aunt or great uncle.
You aren't. You do not share a common ancestor.
Since it would be your sister who had the child with her husband (your brother-in-law) then that would make their child your niece or nephew.
There would be no relationship as you do not share a common ancestor. If your brother-in-law is married to your sister, then her daughter is your niece, her husband would be referred to as your niece's husband.
Generally, the niece and nephew would be the heirs at law under the laws of intestacy. You can check your state laws at the related question link below.
You would be her aunt. She would be your niece.
Nothing, you are not related, unless the baby is your sister's baby as well, in which case they would be your niece or nephew.
If your brother-in-law's daughter is by your sister, she is your niece. If your brother-in-law's daughter is by someone else, she is genealogically not in your family tree.
Your daughter-in-laws sister. There is no relationship as you do not share a common ancestor.
If you they are also the son of your brother, he would be your nephew. Otherwise, there is no direct relationship, though referring to him as nephew (and you as aunt/uncle) would be the standard in most families.
Nothing. Your niece in law. Your brother in laws niece.
Is your wife the mother of your daughter? If not, the two are not related and could get married. If she is the mother of your daughter, or has adopted her, she would be considered a first cousin. In many places, they could get married without any problem, but check your local laws as some places do not allow first cousins to marry.