My mother in law wants my sister to be her 2nd daughter in law .. 😐

In our culture arranged marriages are common. I was arranged married to my hubby 5 years ago ( we got to talk and meet before tho ) he had a older brother whose like 29 and my mother in law asked me about her hand in marriage , now I already my moms and my sisters answer , it’s a big no. Because 1. His brother is not even educated, he did like high school and she’s becoming a nurse 2. He’s really big like 300lbs and she’s a tiny 3. He has a bad habit of smoking drinking being with random girls and all , my family would never agree. I honestly got the good brother.

But idk how to tell her don’t even think about it without ruining our relationship because we have a good relationship . We talks for hours , we can talk about anything she’s like my second mom. I just don’t want to hurt her or make her feel bad so I said “ I don’t know it’s up to my mom , talk to her. “ she’s like yeah I know but your her big sis too so your gonna be involved too because your already in our family.

I hate how she’s has this wish of sisters marrying in the same family so we can all get along but I also know my family would NEVER agree. I mentioned it to me mom once as a joke and she was like not In a million years. My sis turned down guys who were settled and educated so why would she agree to someone who gets money by doing illegal things. I hate how I’m in this situation