I think that could be a strong topic, especially if you focus on the positives. So rather than focus on the extra responsibility, focus on positives. Don’t get caught up in the temptation to write “how this difficult time helped me grow as a person”, but really think about what your sibling did for you.
For example, imagine a sighted person who is going on a hike with a blind person. They could talk about how this made them more aware of the limitations of the blind person, helped them become more responsible, etc.
Now think about an essay about the same experience, in which the person who can see writes about how they learned that each area had its own smells, how the sound echoed off the trees and other features in different ways, how they discovered that there are so many other things going on, of which they were not aware, since they were focused only on what they could see.
Which of these two descriptions do you like better? On the technical side, which of these lends itself more to “show, don’t tell”?