It's in season 5 that it was said that Alexis visited Roger Grimes in the hospital. Blake forgave Alexis for her affair with Grimes but three months after he found out that she visited Grimes at Grimes at the hospital and assumed she had pursued their affair so he banished her for good. These details were created to make us sure that Roger Grimes could not be Amanda's father. That's just your theory. But I doubt this how the Shapiros and The Pollock envisioned it. There are a lot of discrepancies within "Dynasty" itself and I don't think we can say that season 9 exists in a different universe that season 5 for instance.