This is why I wrote the post.
Looks like they are already talking about a batwara type thing, thanks to Dharmesh.
This is where Manohar and Sulo need to be strong and unmoving in their decision to leave the house to Archu. And be quick about it.
Get to a lawyer before they do. Draw up the papers quickly, let Manav go with them to a lawyer, but they shouldn't tell him what they're doing, or he'll talk them out of it.
Archu, out of the goodness of her heart may say no, but in the long run, this is extremely importantly for her, she MUST have a roof over her head. I know Manav will provide her with a home, but after seeing how her siblings and their spouses (except Satish) have turned on her like tigers, the house must go to her.
With no formal education, like her sisters who went to college, this is an investment in Archu's future safety and protection which must not be ignored at any cost. This will also help her when the kids come, Manju won't get the chance to hurt her or Manav and they can live there with Manohar and Sulo in peace.