Family problem.

Assalamo alaikum,

I am wife of younger brother staying with Mother-in-law and husband. My elder brother-in-law stays away with his family. He is well settled with a government job.
My father-in-law separated when the sons were young and did not contribute anything towards the family. The elder son got the job in his place. My mother-in-law along with her sons built a house. My husband earned very less at that time but he contributed a high percentage of his salary as compared to his brother who earned well at that time. We are staying in that house
We married in a very simple way. Because of my husband's low earning , I took up a job. As I am well qualified, I am earning well. So, we built another floor with our money.

My brother in law's family keeps visiting us very often. My mother-in-law keeps supplying them with household items without our knowledge. This has become her regular habit.

This makes me very angry as they are well settled while I work so hard throught out the day. Please let me know whether it is correct on my mother-in-law's part. 

Wa alaikum salaam Ms Sjm, and welcome! Given that she is the undisputed matriarch in the family, and assumingly she is simply facilitating others by loaning a pot, dish, or some inconsequential household item, it is better that you happily accept the blessings from Allah which you receive via her largesse. When you need those items for usage, simply ask the family if they are finished using the given item. Things come and go, but family is infinitely more important than a colander you may have recently purchased.