Bad decisions and MLMS

I love my sister but she just keeps making bad decisions. She’s honestly turning into a meme. She met a guy(who already had 3 kids with 2 other women) while living out of the country, got pregnant and through a series of manipulations and lies ended up a single mother because she was pregnant with a girl. He wants nothing to do with his daughter at all. She moved back home and in with my oldest sister. She lives rent free and contributes nothing to the house hold. Manipulates my sister and parents into caring for her child. Bought a brand new car she can’t afford when she had a perfectly fine car that was paid off, if needed minor repairs like brakes and shocks. She always complains about lack of money (she started a go fund me so she could move into her own place) but when people offer to help her get a higher paying job(helping her with a resume or suggesting job openings), she complains she won’t be able to find child care for those times. She’s currently a waitress and laid off but is scheduled to go back to work soon. Now she says she can’t do full time waitress job because they will cut her unemployment. Her solution: a 15 hr work week and selling for an MLM (Scentsy). Overnight every Facebook message is her guilting her friends and family to buy so she can be a “stay at home mommy”. She’s becoming ridiculous entitled and constantly starting fights with my oldest sister. Most of the arguments center around her buying useless junk that is taking over oldest sisters home. Oldest sister has anxiety and depression, this living arrangement is stressing her hard but she would never throw her niece out. My niece is nearly three is nonverbal and they still haven’t attempted to try to potty train her. I just keep watching her spiralling getting worse and worse. She’s not a bad person, honestly I think she could benefit from therapy for her shopping addiction and maybe cutting out some toxic people talking her into bad decisions. I want to help her, but I’m not just going to throw money at the problem and hope it works out, especially if it means buying smelly air diffusers she only collect a meager commission on. Has anyone else had a family member like this? Any advice will be appreciated