MidGard
I think the way for Asna to get access to the UVR is to ask felix to willingly hand over the control of his body, but the danger in this is that Asna need to also be willing to give back control after so Felix may be reticent to agree if it’s Asna, seeing she already tried to fool him by amassing energy to take over the control forcefully.
Why not leave his subordinates to reach peak sixth stage of replacement with normal bloodlines and then use primogenitor bloodline to replace the last normal bloodline, reaching seventh stage of replacement. I think their 1% human blood can support a normal tier 7 beast if they use the primogenitor as a seventh replacement bloodline. They will be stuck at replacement stage since their 1% human blood etched with normal beasts can not consume the primogenitor blood. For Felix that has used every replacement stage a primogenitor bloodline his 1% human blood should be very powerful to consume a single primogenitor bloodline so he will have it easy to get to origin realm.