she would be your half-sister (since she shares half your blood)
Second cousins once removed.
Hes now relation to you really. You dads sister would be your auntie You aunties daughter would be your cousin I think you could call him cousin in law but im not sure Yes, you can call it cousin in Law.
your uncles daughter would be your cousin
you would be her aunt and she would be your niece
A Great half uncle.
Since your uncle's sister is your aunt, her daughter would be your cousin, just as your uncle's daughter would be.
niece/nephew
A cousin, in all those difficult cases they are your cousins
It would be a second cousin.
She would be your 2nd cousin.
The relation of the mother;s sister to daughter is niece-aunts.
Being your sister's brother or sister you would be an uncle or an aunt to her daughter.