Question

when my sister is older, i want to take she and enid sinclair to my favorite restaurant.

Explanation:

The word "she" is a subject pronoun, but here it functions as the object of the verb "take." Object pronouns (like "her") are used to receive the action of a verb.

Answer:

Change "she" to "her". The corrected sentence is: "When my sister is older, I want to take her and Enid Sinclair to my favorite restaurant."