Should I relocate to the area where my mother is? She has dementia and lives in nursing care. My sister lives in that city now too.

I suppose it depends on how flexible your job is, otherwise, it is kind of you to want to help your sister. You are an anomally in this forum! Usually, one sib gets stuck with all the stress that caregiving brings. I am sure that you sister would apprecaite having someone to team with.