If she has a will, then the instructions in the will must be followed. Otherwise, the children will normally go to their father(s), if living. If not living, then the children will normally go to the maternal and then paternal grandparents, if living. If none of these people are able or willing to take care of the children (when there is no will), then the court will decide who to place them with, considering siblings of the parents, etc. You would need to get a lawyer, and the court would need to appoint a lawyer for the children as well.
Yes.
the father gets the custody of the child if the mother dies
If the courts gave you your rights to have your kids, than your sister has no legal standing to keep your children from you. If she refuses to give you your children, you need to call the police because that would be considered kidnapping to take your kids and keep them without legal custody.
Without a Will, he has no clearly defined custodial rights to a stepchild, but unless addressed in a custody decree, neither does the father. Guardianship reverts to the maternal grandparents.
The mother. If she dies, her parents get custody.
If you live in the US... Children are not property and therefore cannot be 'willed'. You can state in your will who you would like to receive custody, but the court is not required to abide by it. For example, if Mom has custody of a child, she dies and her will states that she wants her sister to receive custody, but Dad wants custody...Dad gets custody, unless he can be proved unfit, because Dad has first legal right to custody (Mom's wishes don't change that).
She has split custody of her kids with Kevin Federine
It has never been mentioned on the show. As they have never mentioned the kids visiting their dad, I assume he does not have partial custody of them.
I believe that Leland and his ex-wife Maui share custody of their kids
Abraham's sister dies by giving birth to her child.
Yes you can gain custody of her.
She already has custody of her children.