Upper Ball Joint keeps coming unseated

[TexasState]

So I've been working on my parents' pickup, and their old 1998 Dodge Ram 1500 2x4 was making an awful creaking sound like you would not believe. Determined it to be the ball joints on the passenger side. So I replaced the right-upper ball joint (only the one because my parents are paying for the parts and are reluctant to invest more money into a 16y/o pickup) and while the creaking improved, it was not completely abated. I convinced my parents to let me replace the lower one as well. When I took off the tire to replace the lower ball joint just one day after having replaced the first ball joint, I realized that the upper ball joint I had just replaced had come unseated and was then torn up by the spindle and control arm. Thinking it was a defective part, I returned the upper ball joint when I went back to Advance Auto, who replaced it. I then installed both a new upper and lower ball joint that day. This was all just a few days ago and while my mom was out driving the truck yesterday she said she heard "strange noises" coming from the passenger side. I drove the truck myself and sure enough, there was audible thumping/knocking from the passenger side and the truck was pulling quite a bit to the right. Took a look behind the tire and sure enough the upper ball joint had come loose again!
I have no idea what to do! I feel bad because I convinced them that these repairs would be worth it but it is turning into quite the headache. I doubt that it would be a faulty ball joint two times in a row but I was positive that the new ball joint was completely seated when I put it in the second time. Has anyone ever heard of a problem like this before? There are no bolts or welds holding down the upper ball joint so I'm not sure what is supposed to keep the joint in other than the torque applied to the joint when installing it. There are a bunch of small grooves around the edge (like the edge of a quarter) which I'm told are there to hold the ball joint in place however they don't seem to be working.
I've attached a couple pictures of its current state.
Thoughts? Suggestions?
Please help, my parents will kill me if I just broke their truck :/

 

[NYCruiser]

How hard was it to remove the old and press in the new ball joint? I'm thinking the control arm is shot. Like the BJ hole got enlarged by the warn ball joint knocking around for too long.

 

[TexasState]

It was unbelievably difficult to remove the old upper ball joint - but not from the control arm. It was stuck like nothing I'd ever seen in the spindle. I actually had to saw the old one in half with a reciprocating saw and use a pitman arm puller to pop the lower half out of the spindle. The upper half came out with some moderate hammering.

 

[98blackbeauty]

I had the same problem on my 98 4x4. Are you possibly using Moog or O'Riellys house brand?

 

[meistermash]

Smash it back in and then tack weld it a couple of spots.

 

[LB3711]

looks like the wrong part to me. If the control arm around the hole is 100% intact the ball joint should press in place.