If teresa’s daughter is my daughter’s mother then what i am to teresa

If Teresa’s daughter is my daughter’s mother then what i am to Teresa?

Solution:  Daughter

Imagine you are Teresa's daughter say your name is 'X'. Imagine I am your daughter and Teresa's granddaughter let my name be 'Y'.

Then,

Teresa => X => Y

Teresa's daughter is X.

X's daughter is Y.

Thus, Y's mother is X.

Therefore, you are Teresa's daughter.