Question about Mom's cigarette addiction?

My mom has smoked since she was 18. She is 85 now, and I am her primary caregiver. She suffers from COPD, Asthma, Emphysema, and has most recently displayed symptoms of dementia. She was hospitalized in February of this year for a 2nd round of pneumonia. This was followed by a 21 day stay for rehab in the nursing home because she was too weak to even walk when released by the hospital. Through all of this, she continued to ask for her cigarettes. (she was on oxygen.) I decided when she came home that she would not smoke any more; I threw them all away, and asked the dr. to prescribe the patch, which the dr. was happy to do. My mom's COPD/Emphysema/Asthma is a direct result of her years of smoking, and once I took her cigarettes away, her health improved. She stopped coughing/wheezing, was able to be removed from constant oxygen, and had a general improvement overall in her health. She has continually denied that smoking had/has anything to do with her medical condition. Up until this month, she has been smoke free, almost 7 months. I had a 2 week vacation planned, and my siblings agreed to take care of mom over this time period. I went over everything with them, and told them that she could not smoke at all, that if she asked, they could not give them to her or buy them for her. I am in the 2nd week of my vacation, and my mother sent me a text that she smoked 2 cigarettes today, and that it didn't affect her oxygen level at all. I am just beyond belief upset that my siblings totally ignored everything I said and gave in to her. My one sibling actually took her to the store to purchase the cigarettes. (My mom is not able to drive, and has to have a wheel chair when in a store.) My siblings response was, "Well, I couldn't stop her." My mom did not wheel herself to the counter to purchase those cigarettes. Like I said, I care for my mom full time, and all I asked for was 2 weeks of vacation, and then get this dumped on me half way in. Has anyone else had to deal with a parents addiction to something that was directly contributing to their disease/disorder/health and well being? Was I wrong for just taking the cigarettes away in the first place? (No one in my household smokes, and she was never permitted to smoke inside.) I'm not sure what to do from here, but like I said, now my mom thinks its OK for her to smoke.