One of the biggest issues I'm seeing here is you got one snake, then another a couple of weeks later and you're housing them together immediately. Housing communally isn't a good idea ever but doing this means you've done no quarantine with the new snake at all. Even housed seperately you need to follow quarantine procedures anytime a new snake comes into your home, even if it's from the same source. You have no idea what either snake has been exposed to. To toss another snake into the tank of the first snake is playing with fire, and in the end the snake's will pay the greatest price (though your mother may well if she has to foot any vet bills).