Selling of fully paid property in QC

We have a house and lot in QC, around 27 square meters. It's an awarded lot from National Housing Authority to my grandmother (mother side). Since my grandmother is incapable of paying in full, my mom paid everything (using my deceased father's money).

My mom has 3 sisters (1 died in 2010). Before that, my dad talked to them (with my grandmother) and proposed an agreement that he will pay for the lot, but they will have to waive their right to it, which they all agreed, they signed an agreement(notarized).

Around 2006-2007 we started to process everything for the title to be in my mom's name.

However, my mom has a 30+ y/o niece whom my lola took care of eversince. She's the daughter of my uncle who passed away a long time ago. My lola wanted another agreement that my mom will only have the right to have the title under her name alone if her niece will be allowed to live there. Because we have no choice, we agreed.

They then signed another agreement saying that my cousin is now waiving all her right on the lot title and in return, she will be allowed to live there.

Now, my mom is sick and my cousin had the other room rented by a family without our consent. We want to sell it, since we all have the documents and title. I am now in Laguna and my mom is living with me, but she sometimes go to our house in Quezon City.

Question:
-can we now sell our property since it is under my mom's name?
-when i told our relatives that we are planning to sell it, they reacted negatively esp my cousin who believes that the other room is her property, but what is on the agreement is her right to live there ONLY.
-if ever we sell it and the title is transferred to another name, will the agreement still be valid?

please help.

This is my interpretion:
The hiers of lola (=your mother's sibblings) had vaiwed their OWNING rights allready, so the signature of the niece wasn't needed,
But both say the same anyway = Niece is allowed to live there. I suppouse with no time limit.

(I'm not sure, but I guess it can be compared with a long time lease concerning if selling = The niece have right to live there until she die UNDEPENDING of who is owner. This make the property very hard to sell, I suppouse.)

But you can try to offer a compensation the niece find interesting enough to vaiwe her right to LIVE there, but the niece don't need to accept.

But the niece don't have right to rent out to other, without your approval, and the rent money belong to you.