Thank you all for your support and help. The girls do know a bit, as I do have to ask them to step up more than usual. They help with dinner, open my jars, drinks, and anything else that requires the slightest effort of the wrists/thumbs. They cut me slack, and are understanding if I need to take a nap, I think they might even enjoy the unsupervised time that allows.
We just haven't had a "real" talk about it. I'm afraid of not being able to answer their questions, and scaring them more by not having the answers.

The overwhelming advice is to be honest about it. I agree. I just don't know "how" right now... So any advice on the how part?

Thank you to everyone! You all are so wonderfully supportive.