Paragraph 1: I always drink coffee in the morning, but my sister doesn't like coffee at all. She likes tea instead.
Answer: From the above sentences, the nouns/pronouns used as subjects are 'I and My sister.' The pronoun 'She' is used to replace the antecedent 'My sister.'
And yes, the predicates agree with their subjects and the pronoun agrees with its antecedent.
Paragraph 2: I am married, but I don't have any children. My sister has two children, so she is busy with them in the mornings.
Answer: Again, from the two sentences above, 'I and My sister' are still the subjects. Also, 'She' is used to replace 'My sister.' 'Them' in this case is a confusing pronoun, as it doesn't explain who or what it is referring to.
Finally, the predicates agree with the subject and the pronoun 'She' agrees with the antecedent 'My sister.'