I know many of us (including me) are leary of Bordetella (and other vaccinations)-but it's necessary where I live. Both my dogs go to doggie daycare-and you never know who is bringing their dog there, and what their dog might have. Our local dog park requires that the dogs be current on vaccinations, and the groomer requires current shots and bordetella vaccines in order to get their hair cut.
I talked to my vet about it-(the new vet, who was WONDERFUL), and he said that he likes to give each vaccine as a separate shot-no combination ones. Also, the bordetella can be given as a shot or as nose drops-talk to your vet about the options and the reasons for each. Emma & Milli got the nose drops in the past, but the new vet recommended the shot this time.
Also, if you're worried about reactions, maybe do only 1-2 shots at the same time, and then go back one or two more times for the others that Layla needs. Make sure to wait 30 minutes at the vet's office after the shots to make sure she's not going to have a severe reaction. That way, if she does have a reaction, you'll be able to pinpoint where and what caused it. Also, if you wait at the vet's office, they will be able to help her if she has a reaction to something.
My vet had us wait 30 minutes after vaccinations for Emma and Milli-it pretty much took that long to finish looking them over, get flea/heartworm meds, and get checked out of the vet's office anyway