Living with 3rd Brother in Law & his wife??

Everybody in the Tan family is eyeing my spare room!
The eldest brother, my MIL etc. My MIL even suggested $300 for rental..

The 3rd brother recently got married. Wanted to buy a flat but did not have sufficent cash as prices of flats are on the high side. Hence they are looking for a place to rent.
His wife is a Myammar nationality who can speak Mandarin.
I am in 2 minds whether to rent to them.

Advantages
- she can cook.
- she can help out in household chores
- Mico will have someone to accompany her. Most probably she will be another housewife in the Tan family. All the Tan family women r housewives except for ME!
- I will get into my MIL good books by renting out to them. Next time got baby can throw to her or this 3rd sis-in-law can be caregiver too..hahah
- will not be so bored at home since got company
- get $300 for rental as suggested by MIL.

Disadvantages
- $300 is insuficient to cover additional bills eg aircon, water, gas, electricity
- total loss of privacy!
- I don't even know the name of this sister in law. The Tan family man hardly talks. Boring kind of company
- Don't know how modern this woman is. If she knows how to use my machines, various types of detergent etc.. What if my white kitchen turns black!
- Will i have to spend extra on food - Hubby does not give me allowance. What if she eats all my stuff and never replenish???
- Will she torture my Mico?? Will my Mico run out of the house if she opens the door when I am not around??
- Is she going to do housework or simply a lazy woman who bochap?
- hubby will be damm lazy. Once got additional hands to do housework, he will simply bochap anymore. It's hard to train a man to do housework. Give him an additional pair of hands to help out, he will simply bochap
- When will they buy their own flat & move out?? Will they encroach on my space forever???
- maybe I won't even want to come back to my home after work...
- what if they destroy the laminate flooring in the room??


I don't want to pay for my reno loan liao if i don't even control who gets to stay in my house.
How??