In both life and metalworking, I find it easier to prevent problems
than to fix them. So, my suggestions would be in the area of
Use something which does not disappear at soldering temperatures
to mark the placement. For instance, I like to use a pencil to draw
"cross-hairs" indicating placement of a post or pin finding, with a
circle around the spot where I want it soldered. White Out/Liquid
Paper and yellow ochre could also be used. Sharpie tends to fade out
at annealing temperature, but Bic pens don’t fade as much, so you
could experiment with different brands of permanent markers.
Use a graver to raise “stitches” to hold the piece in place.
Solder wire “pegs” onto one piece. Drill holes through the other
so that placement is exact. Rivet, melt the ends of the wires, or
solder the pegs with a lower temperature solder.
Hang in there. Each metal has its pluses and minuses. That’s why we
each have our favorites, and that is what keeps life, and this forum,