first off, there are images attached for best description of the problem. The setup is: The 1/2 inch copper pipe connects to a threaded joint on the shower valve (1 inch), easy, right? Except when I try to replace/rebuild this assembly (it is leaking at the joint, see picture), I cut it out and take it to HD/Menards: they say they don't know how to replace it or what the connecting bit really is. It seems like some random threaded part that was soldered on top of the pipe.
I can't solder, is there a way to rebuild this joint using pex or sharkbites or something else? Or I can only solder electronics, I doubt it's the same-never tried it.
EDIT: the manufacturer seems to be selling a very similar/ updated version of this at https://www.pioneerind.com/product/three-handle-tub-shower-set-2/#0868-Z, but the installation guide is not clear on how to connect the 1/2 inch supply lines.
Thanks a lot!