Family Frustration

I've posted on here before about my frustrations with my son and the mother of his child. Just prior to him leaving for college, he tells me this girl is pregnant. I'd never even met this girl before. Anyway my priority has always been school for my kids. I had him when I was in my second year of college and didn't quit then so I didn't want him to quit. I said I'd be there for her and the baby but the agreement was for him to come home after graduation. Well he's graduating and of course he's changed his mind about coming home. He found a gf and they've had two babies within the past 18 months....no lie. So I'm disgusted with him. The mother of my first granddaughter has turned out to be a TERRIBLE mother despite having help and my granddaughter living with us every other week. Apprently when she's with her mother, she's missing school. She's missed 34 DAYS of school!!!  She never misses on our week except when she's actually sick but I always call the school and that's only been a single day this year. I suspected it and asked my granddaughter did mommy take her to school. I think she's been lying to me. Now the school is threatening to make her REPEAT KINDERGARTEN!!! 😳. Who the fuck repeats Kindergarten?!?!  She's doing well in school despite the missed days but it's a rule or something. I know she loves her mother but I suspect she doesn't get a lot of attention from her. She's with us more and more and now it seems her Mom hasn't been taking her to school when she's with her.