No way would I apply a chemical to any part of another person's body. I don't need the melodrama if something happens to go wrong. I won't flatiron/hot comb anyone else's hair either. Blow drying is the most I'm willing to do as far as hair appliances go. Oh, I'll braid, twist and roller set, but you can't really mess those things up. My own mama once burned a section of my hair when flat ironing it for my 8th grade graduation. My 14 year old self was pizzed as heck at my own blood mother lol, if it had been some strange chick at the job? Couldn't have ended well lol. You're braver than me OP.
Those are my only thoughts.