Ally's mom,
I am not a doctor, but I can tell you
our experience... Our daughter, Aria, was also born in August with an OBPI. Hers was bilateral, but her right arm was much more damaged than her left. We had primary surgery on her right arm with Dr. Kozin at the end of January. He did some pretty extensive grafting to her C5 and distal C6, but her C6 root was avulsed, so he also transferred it into her C5. More directly to your question, he transferred her suprascapular nerve into her spinal accessory, to give her external rotators a better chance at coming in strong. (The suprascapular provides power to the supraspinatus and infraspinatus, which provide external rotation to the arm. These muscles are usually the last to "come in", and traditionally suffer the greatest problems with weakness, as the nerve has to regenerate a long, twisty way to innervate the muscles. Many times, a transfer from spinal accessory hastens this process, so the muscles are innervated sooner and suffer less permanent atrophy).
As far as muscle or tendon transfers, his approach is to wait and watch to see what Aria gets back from the primary surgery. While there
is a time limit to primary surgery (as muscle which is not innervated dies at about 12-18 months), there really
isn't that time limit for muscle and tendon transfers.
I don't know all the specifics of Ally's injury, and there is a good chance I just spouted off a bunch of stuff you already knew...
In any case, for Aria, we want to see how much recovery she has from her primary before we make a decision on secondary surgeries. (Dr. Kozin feels she almost certainly will need some muscle/tendon work - but he also feels secondary surgery will have a better success rate when Aria is old enough to follow instructions and be a more active participant in her PT program.)
I'm sure this message is a bit rambling... sorry. If you want to, please feel free to e-mail me directly. I'd be happy to answer any questions you have about our experience with Aria's surgery thus far.
Keep in mind as you make this decision - every parent here is doing the very best they know how to do for their child. And, we all make different decisions as far as surgeries, therapies and doctors. The fact that you are here on this board, and searching for answers means you are trying so hard to do the right thing for your precious Ally.
I wish you luck in this decision - and great success your little girl.
mica