I will be working as an independent contractor for my brother and receiving a 1099-MISC. I also will be receiving a 1099-K for reselling items for profit. 

My question is this. I live with my mother and take up a considerable amount of her house as storage for the items I resell. Can I claim the office space as a deduction even though I don't pay her mortgage? What about other expenses like a portion of the utilities?

If I only can do this if I am paying her rent then does she have to claim the rent as income?