The Challenge is to have the HRE take over England instead of the Normans. Is this possible, even if it's difficult? And if so, what would be the aftermath in England?
OK
1 Have Edmund's first marriage to Aelfgifu be as childless as his second to Aethelflaed. So no Eadwig nor Edgar
2. Eadred dies a bit earlier than OTL in 952AD.
Now this is crucial as it is BEFORE Luitdolf rebels against Otto I. As Luitdolf is the grandson of Edward the Elder through his mother Aedgyth he now probably has the best claim to the throne and probably the backing of Otto to preempt a rebellion.
Job done.