Navigating Family Expectations as a Widow

Assalamualaikum everyone. I'm a widow with two kids-a daughter who we need to get married soon, and a son who just finished high school. Currently, I'm living with my in-laws in a joint family setup. My own brothers have made it clear they won't take me in or help with our responsibilities. Lately, my mother-in-law has been suggesting that I marry my brother-in-law, who's almost the same age as my daughter. She says this is the only way they'll continue to support us and take responsibility. According to her, he's also getting older for marriage, and if he marries someone else, that new family will have their own separate needs to care for. For those wondering about legal rights or my share of my late husband's wealth, honestly, we don't have the legal advantage or the funds to pursue any court cases. Just trying to figure things out with sabr and dua.