She relies on her sister to drive her to school
She relies on her sister to drive her to school.

Does the above sentence mean:
Her sister drives her to school?

or
Her sister drives other person to school?Sorry. forgot to put parenthesis

Does the above sentence mean:
Her sister drives her(She) to school?

or
Her sister drives other person to school?

Question

She relies on her sister to drive her to school
She relies on her sister to drive her to school.

Does the above sentence mean:
Her sister drives her to school?

or
Her sister drives other person to school?Sorry. forgot to put parenthesis

Does the above sentence mean:
Her sister drives her(She) to school?

or
Her sister drives other person to school?

Answer

To understand your sentence better, suppose that 'She' means 'Jessica'-(name of a girl). Now, your sentence will be "Jessica depends (relies) on Jessica's (her) sister to drive Jessica to school.". So, it means "Jessica's sister is driving Jessica to school."

Answer

I'd assume that her sister (female 1) drives her (female 2) to school - two women. But it depends on the surrounding sentences. If we had more information such as, "my friend (female 1) has a daughter (female 2) but no car so she (female 1) relies on her sister (female 3) to drive her (female 2) to school. Context is key. :)

Answer

"She relies on her sister to drive her to school" means " Her sister drives her to school "

Answer

Her sister drives her to school.