The more Shinkis I get, I'm starting to think that breaking either a connector peg (this thing: ) or a leg joint (this: ) is inevitable no matter how careful I am. Is there any way to fix these if they do break? I don't mean if they just get loose but if they completely snap off. Thanks in advance.

Pegs could be fixed by pinning a spare bit of plastic rod the right size into place (get a pin vise, drill out a small hole into the peg and the piece you're attaching to, glue replacement peg into place with a bit of brass rod in the holes to reinforce it). The sprues for the extra connector bits are perfectly sized for this kind of thing (their cross-section is identical to a standard shinki peg).

The hip joint pieces... Can't think of any method other than scavenging parts from another shinki (or spare blank body or whatever). But you'd have to use some serious force to break them, they're made out of incredibly tough plastic.