Phil0110

Jen, have you considered using another fabric to "enlarge the shirt to get it to the width you need?  You could use the sleeve design in this same block, or elsewhere in the quilt.
I made this T-shirt quilt for my niece, and used a collar shirt in the lower corner.  I used another part of the shirt to fill in the neck opening, and had to trim and restitch the collar at the top to make it lie properly.  This slippery material did not lend itself to being fused any other way.

Phyllis,
I would suggest to your friend and her son that they not desecrate the flag of the United States of America in this manner.  
As the potential quilter, I would abstain from taking part in any portion of this project.
As an individual who has signed their name on one of the blank checks that has contributed to giving you, your friend, and her son the right to even consider this disrespectful treatment of the flag of the United States of America, I would never use or recommend any quilting business that took part in this despicable treatment of the flag.
I believe your request of information is so contrary to spirit and intent of the hundred of thousands of "Quilts of Valor" that have been lovingly made and presented to our veterans of the United States Armed Forces.  
If your friend wants to make a "throw" for her son, she should make a quilt that honors and respects the symbol of our great country of the United States of America.  Her son can soil her quilt by lovingly using it as the body covering it is intended.  
The young man can proudly and properly displaying the flag of the Unites States of America on his wall, and remember all the outstanding men and women who have served our great nation.  Family and friends will not be appalled upon seeing the flag of the United States of America being used as the suggested "throw" covering.
You may not like my blunt answer, but I for one feels it needs to be said.  To do otherwise, is to consent to disrespecting the flag of the Unites States of America in this manner, and dishonoring all those who made the ultimate sacrifice to make and keep us free citizens of the United States of America.
Besides this one, I wish you all the best in your quilting endeavors.
Cagey
"The flag should never be used as wearing apparel, bedding, or drapery."
https://www.law.cornell.edu/uscode/text/4/8