Final answer:
To maintain a grammatically correct sentence, you should add a comma after 'Shazia'.
Step-by-step explanation:
The correct revision to maintain a grammatically correct sentence is to add a comma after 'Shazia'. This will ensure that the elements in the sentence are properly separated. The revised sentence would be: 'I am planning a trip to London with my uncle, Shazia, and Nanette.'
Learn more about grammatical correctness in sentences