yourself
No, in the comic series, Bruce Wayne was an only child. His parents were murdered while he was still young.
You
It depends on what other family is still alive. If there is an aunt or uncle - or even an older sister or brother - so long as the prospective guardian is over 18, they would probably be granted guardianship. If there are no surviving relatives, the child would be cared for by the state.
If your sister-in-law is still married to your brother and her daughter is the biological child of your brother you would be the child's great aunt or great uncle. If your sister-in-law is the sister of your husband, her daughter's baby is your great niece or great nephew, and you are the baby's great aunt or great uncle.
No, you cannot. An adopted child is considered a child of the parents in every legal sense. And you cannot marry a sibling. Actually, apparently you can. Look at actors, Linday and Bryan Price. Their parents were brother and sister by adoption. Their mom, adopted from Korea by the Price family married her brother. So, apparently, yes it is possible, under what circumstances and what they had to do to accomplish this I do not know.
Kimora Lee Simmons is an American entrepreneur who was a model in past years. She has mixed heritage, Asian and African-American. Her parents divorced when she was still a child and she reportedly has no siblings.
If this adoption is just recent, he is still your brother which makes his wife your sister-in-law which makes her parents nothing to you. However if you have grown up (since near birth) with your brother acting as your 'dad' and his wife as your 'mum', then with respect to her parents, they are your grandparents.
No here they are still brother and sister, but they do have a stepfather.
That might be difficult, depending on how old the child is. Convince him that he/she can play with their new little brother or sister. Also say that you will still spend as much time with he or she.
* No, she is not longer your sister-in-law, but you could still remain friends and introduce her as your ex sister-in-law.
After your brother dies, his wife is still your sister-in-law. If she remarries, you or she may find it convenient to think of her as your former sister-in-law.
no. They are brother and sister.