yes she can
yes
yes
Yes my mother in Law is Godparent to her ten years younger sister
The daughters of your sister are your nieces.
Yes, however at least one godparent must be Catholic.
You would call your sister's daughter your niece.
The word godparent isn't a proper noun therefore it shouldn't be capitalized.
To your sister's daughter you are an aunt (or uncle) and she is your niece. To your niece's daughter ( your sister's granddaughter) you are a great-aunt (or great-uncle) and she is your grand-niece.
There is no relationship at all.
You have to have at least one child in school. Then, you go to the babies page that you want to be the godparent of. If they don't already have a godparent, there is a button that says "Become godparent". Click it. A message will be sent to the owner of the baby, if they confirm it you have a godparent! Send them gifts! Add me! Charcharkazoo
You must send a baby to school before you can be a godparent.
Where "godparent" is recognized by a faith community, check with your local pastor. In civil society, the choice of a godparent is entirely up to the parents.
She is your third cousin.