My older brother passed away six months ago. He was still young, but he lost his battle with cancer and could not be saved. My brother had been married for seven years and had two children. He was also the only son in our family. Thankfully, my parents still have two grandchildren, which somewhat eases the pain of losing their son.

Recently, I’ve noticed that my sister-in-law has often been bringing a strange child to our house. The child is younger than my two nieces and nephews. My sister-in-law and my brother had one son and one daughter. Since the child was unfamiliar, my nieces and nephews were not close to him at all. Seeing this, my sister-in-law even insisted that her own children approach and befriend the boy.

I asked my mother about the child’s identity. She told me that he was the child of one of my sister-in-law’s colleagues and that she was just looking after him for a while. But somehow, I felt that things were not that simple.

I noticed that my sister-in-law treated this child with unusual tenderness. At times, she even asked her own children to give in to him. Her behavior felt strange—too attentive, too deliberate.

Unable to keep guessing, I took the opportunity one day while we were cooking together in the kitchen and quietly asked her whose child he really was.

She fell silent. After thinking for a moment, she leaned closer and whispered the truth into my ear.

I was completely stunned.

That child is the son of a man who works at the same company as my sister-in-law. She and that man are currently seeing each other, hoping to remarry in the future.

She told me that her colleague had divorced his wife many years ago. His ex-wife has since moved abroad and remarried. After my brother passed away, this man frequently checked on her, comforted her, and supported her emotionally. She plans to make their relationship public in a few months, announcing that they are preparing to remarry.

That means she intends to move on and remarry before even a full year has passed since my brother’s death.

Now I finally understand why she keeps bringing that child to her former in-laws’ home. She wants her children to get used to the child who may soon become their stepbrother.

I was deeply shocked. Technically, both of them are single, and she has the right to pursue her own happiness. But I cannot accept the idea of my nieces and nephews following their mother to marry another man.

My parents have already lost their only son. Are they now supposed to lose their grandchildren as well? More than that, I don’t want the children to grow up in a complicated situation of shared and stepfamily relationships.

I told my parents everything. After that, we held a family meeting to talk things through with my sister-in-law. However, she showed no consideration for my parents’ feelings at all. She insisted that she could never live apart from her children.

Now I’m at a loss.

What should I do?