The 2 wires from the female charge port can I solder them onto the positive and negative wires between the Antispark and the battery
Need more then one sentence to be sure what you mean, not familiar with your setup.
10s battery to anti-spark switch to 2 vesc xt 90 connectors through out
I am not sure if I understand the question, but why not use xt90-S with built in anti spark?
If you're wondering if you can connect the power supply for two VESC in parallell before the antispark, then the answer is yes. Aslong as your battery is rated for the current needed to run both at peak performance i dont see any trouble with it. I have one setup with 10s4p that has a max continuous drain of around 60A.