Is it OK to use hairspray to hold a comb over in place to cover a new transplant?

You didn't mention how long ago your procedure was.If it was less than 10 days ago I would not recommend using hair spray as this could be sticky and physically dislodge grafts.After this period you can use any product you like without worrying about harm.Hairspray in and of itself will  not interfere with graft growth.

It is best to ask your surgeon about post operative care as each doctor has their unique regimen.  There should be no issues with using hair spray after about a week.

Generally this is okay to do as long as you have waited at least a week after your transplant, preferably two weeks. Wait until the scabs have fallen off and you are healed before using hairspray on the area.

We
tell our patients that after the 4th day the grafts are set in their
new location.  After all the scabs are
removed and the sites have closed you should be able to care for your hair as
you always did before the transplant.

Yes, once you are a few days from the surgery, the use of a comb to hold a particular style should not be a problem provided that it does not dig into your recipient grafts