GMAT Sentence Correction (SC) | Re: Emily Dickinsons letters to Susan Huntington Dickinson were

Yes, it is alright. This is an example of an exception of the modifier touch rule. Manhattan SC Guide summarizes the common exceptions. Following is an excerpt from the book:

In general, noun modifiers must touch their nouns. However, there are a few exceptions to the Touch Rule.
1. A “mission-critical” modifier falls between. This modifier is often an Of phrase that defines the noun.The less important modifier refers to the noun plus the first modifier
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