Machine sewing over hand sewn seams advice

Hello again! So basically my body suit was like 80% machine sewn and 20% hand sewn.


Here's a reference of the character, I hope it links okay.
It should open to FA with the full image (is that alright?)

The arms were hand sewn to the shoulders, the black forearms and lower legs were hand sewn to the upper arms and legs,
The black parts on the shoulder that "spike" into the white chest area were also hand sewn. And the zip was hand sewn.

I took him to a furmeet afterparty and one of the arm-shoulder seams tore when I was dancing.
So I'm wanting to go over all the handsewn seams to strengthen them to prevent futher seams popping.

I use my grandmother's machine, it is some kind of singer. It can handle two layers of fur relatively easy.


What I'm wondering is if anyone has any advice or tips/tricks for going over existing seams on a machine with minimal allowance?


Or should I just handsew over those seams a few times instead of trying on the machine?

As for the zip, do I need to machine sew that or will it be okay just hand sewn?