A heated grammar dispute over the linking verb “is” in a sentence

[ianconnectsyou]

My officemate and I had a grammar dispute over this sentence that I used as a remark in my report: "John Sorilla, brother of the subject, is the co-maker of the principal borrower." Now, my officemate insisted that I must remove the linking verb "is" because, according to her, it made my sentence awkward to read. I was not in accord with her in that suggestion, so I begged for a clear explanation as to why she believed it made my sentence awkward in construction. Apparently, she was unable to explain her claim, so I justified mine.
I told her that pulling the linking verb "is" out in that sentence would not make it any less awkward, if not grammatically incorrect. I said that the linking verb "is" is very important in that construction because it connected the subject "John Sorilla" to the complement "the co-maker of the principal borrower". I further explained that the sentence falls under one of the seven sentence patterns in English--S LV C--and that removing the linking verb "is" would make the sentence downright ungrammatical. Assuming that it added to her confusion, I went even further to explain that the noun phrase "brother of the subject", which was separated by a pair of comma, is an appositive phrase that explains or renames the subject
Is my assessment of the situation correct? I just want to know your opinion because even though I was able to explain my side sufficiently, I did not win that heated debate. To my surprise, my other officemate sided with her and i was forced in the end to edit my sentence.
More power to you and to this forum!

[Joe Carillo]

If you intended “John Sorilla, brother of the subject, is the co-maker of the principal borrower” as a complete sentence, then I don’t see why your officemate insisted on dropping the linking verb “is” from that construction. It’s a letter-perfect and grammatically perfect sentence as it is; without “is,” the sentence becomes simply a noun phrase: “John Sorilla, brother of the subject, the co-maker of the principal borrower.”

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But then we must view this matter in its total context. Was your sentence part of a narrative, exposition, or dialogue, or was it a stand-alone entry at the bottom of, say, a document meant to identify “John Sorilla”?  If this was the case, you’re absolutely right in insisting to retain the linking verb in your construction. On the other hand, if the construction was simply meant as a label like, say, “John Doe, brother of the accused, defendant,” then there was really no need for that linking verb. The phrase could stand by itself to do the identifying job without need for a verb.

On the basis of the above considerations, I think you can find common grammatical ground with your officemate and not allow this issue to needlessly rankle between the two of you.

RELATED READING:
How English auxiliary verbs differ from linking verbs

[ianconnectsyou]

Thank you very much! I appreciate your response. Now I know that I was right when I insisted to retain the linking verb "is" because that sentence was not part of a narrative, but a single sentence only.

I would like to take this opportunity to say that I enjoy reading your book "Give Your English The Winning Edge". It's a great book, and it immediately ranks as my number 1 favorite among my other grammar books. I wish you write more books about grammar. Thanks!