Navigating Family Dynamics: Adoption, Pregnancy & Unfair Accusations

My husband and I have two and a half kids. My oldest is 10 years old, my middle child is 5, and I'm currently 5 months pregnant. My 10-year-old is from a previous relationship, and my 5-year-old is adopted. My sister got pregnant unexpectedly and saw adoption as her only choice. She didn't want the baby to go to strangers, so I stepped up. We did everything right. My sister went to therapy to consult on her choice, and I went with her to make sure she was sure. We did everything that was recommended for adoptive mothers and birth mothers along the way. It wasn't an immediate adoption; I got guardianship, and we built to an adoption. My sister was involved in the entire process and never expressed any issues in the time it took to finalize. Just over a month ago, I announced my pregnancy. My 5-year-old knows about the biological relationship between her and my sister. Shortly after telling people about the pregnancy, my sister and I arranged to meet up in person in the park. She then told my 5-year-old to give mommy a hug, and my 5-year-old immediately grabbed me. My sister got 'shitty' about it. I asked her what she was trying to do, and she said that I had a baby on the way and assumed that I was done with the 5-year-old and was going to have a new favorite. I said I don't play favorites and don't discriminate between my children based on biological relationships. I explained to her that my pregnancy doesn't change how I feel about my 5-year-old or my 10-year-old. I reassured her that she is still loved and valued just as much as before. But my sister was still upset and accused me of neglecting my adopted child for my biological child. I couldn't believe what I was hearing. I have given my all to both of my children and have always treated them equally. It hurt me deeply that my sister would think otherwise. I tried to explain to her that love is not limited, and having another child doesn't mean I will love my other children any less. But she didn't seem to understand. This incident has caused a strain in our relationship, and I hope we can find a way to overcome it. Love should never be a competition, and I will continue to love and support all of my children equally, regardless of their biological connections.