Slip the strut bolts off and the thrust rods out of the way, then you can get a better whack at it with your bfh! You can also use a drift punch and a mfh ( medium hammer!!) and knock it loose (twist the ears you removed the bolts from! )
Don't forget the liberal application of heat to work in what ever loosening product you squirt on the ball joint.
I've had success with this method ( done dozens of these in the past!) I found that removing the knuckle from the truck , and placing it on a block or an anvil saves the strut from the wrath of the bfh!
Good luck!

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2003 X5 3.0i (02/2003) sport package, Sapphire black metallic / Black Dakota Sport seats. compass mirror retrofit, trailer hitch retrofit, Prodigy P2 trailer brake controller installed, PDC retrofit, Lumbar support retrofit. heated rear seats retrofitted. Running boards retrofitted and subwoofer install in progress. 4.8is Brakes installed front and back. Bluetooth TCU installed, Rear Fog lights installed. Retrofitted reclining rear seat backs.