Any advice on what the weight transfer details are with lifting transferring an MS patient?

I have not done a ton of lifting and transferring, and the husband has already pulled his back out. My gut feeling is no, this will not work. I feel bad as the family that interviewed me fell in love with me and started making schedules, before i could say wait wait, let me think about it. Now, I am not feeling good about it, and want to go back to them, and in fairness, this was a one week trial, and I have a day time job, and this will not bring in more money, just possibly ruin my back. If I ruin my back at 54, the caregiving becomes very limited. Advice ASAP as I need to talk to them this am. Thanks much. MS woman 79 years old, 30 years with MS, just got out of the hospital and rehab for two month's.