Ibiza 6L: Replace Ball Joint (ASZ)

After hitting the curb, I want to replace the left-side lower control arm, including the bushings and ball joint.

Okay, here's my problem: The nut that secures the pivot joint on the wheel carrier is turning and stripping the threads. I need to somehow prevent the threads from stripping further.
The new ball joint uses a size 6 Allen key, which is also available as an accessory.
It's very difficult to see this on a VW control arm, and the axle bushings are supposed to remain in place.

Does anyone know how to counter this thread? What should be used with it?

Thank you in advance!


EDIT:

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It's also an Allen key, probably a size 6. You'll need an extremely short size 6 Allen key for it. But you'll need that anyway when tightening the new ones.

Yes, great, then I'll cut one out accordingly. It will probably go wrong .

Before anyone makes this mistake: it's a 5mm Allen wrench, NOT a 6mm.
Actually, the reason I failed was because I couldn't get the lower control arm stud out of the rear bushing.