What should my response be to my cat's behaviour to the new addition. I have a 5 month old and a 9 wk old. The 5 month old is doing a lot of hissing and growling. I'm trying to let it play out a bit as long as the little one is safe. Should I not behave different to my older one, just remove her if it gets too rough. Tell her no? Try to redirect? Help please!