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But she said even the typing
The typing is about how the body's immune system will react with new blood being transmitted to the body. If it matches then there's basically no risk
These is some info, the first site is about the blood typing
https://www.healthline.com/health/blood-typing-and-crossmatching
https://www.rch.org.au/bloodtrans/about_blood_products/Blood_Groups_and_Compatibilities/
The Abo and typing she is talking about are requirements necessary for a successful blood transfusion. It is preferable that both of those match for compatibility but there are alternatives if that's not the case, having those two requirements perfectly match is rare that's why they mention being fated to be together.
Same with transplants, just because they are family does not mean they will always be compatible, they have a higher chance but not always