Answer:
- Qhamisa is my cousin's sister who is the most beautiful of them all.
Step-by-step explanation:
The given sentence contains a grammatical error in the usage of 'cousin sister.' As per the context of the sentence, the correct form to be employed would be 'cousin's sister' as it is followed by an idea that establishes a comparison. In order to establish the superlative degree, the context of the cousin's must be plural to denote that they are more than two(reflected through usage of all and superlative degree). Thus, the correct sentence would read as:
"Qhamisa is my cousin's sister who is the most beautiful of them all."