Or a partner, a sibling or an ex spouse, etc. 

So, on top of their “right” to move in members of their immediate family (which includes in-laws, step relations, children, siblings etc) they may also move in someone who is not immediate family.

California to find two parents breaking up, lives in disarray, siblings getting devoured by life and addicted to drugs.

I am sure you can, but your siblings will probably have to sign the mortgage as well.

BUT when he & his siblings were kids the father left each one of them a free & clear duplex.

You cannot afford to help out your parents, your in-law parents, your kids, siblings, nieces and nephew much with this kind of money, and we haven't even talked about donations your favorite charities and your goals in your golden years. $10k/month will not get you very far today or in your golden years.

My mom worked as a nursing assistant for quite a while and raised 8 kids, i left home early to go get mine and take some financial stress off her, i know she's proud of what i've accomplished, i have siblings who didn't do much with their lives; i can't say why honestly.

Are ALL the siblings and or remaining relatives in agreement to sell the home?  

This is the only paperwork ever filed and the siblings, children are also deceased by doing my due diligence. 

Nothing like going through probate when the owner passes away and the siblings contest the will.