with a new little one on the way and a toddler still in diapers, should i use separate pails, wash separate or just put them all together in a pail and to wash?

I'd just throw them in together. Using seperate pails for each would probably just make more work for yourself. The only way I'd split them up is if something odd happened- like the new one seems to be allergic to your detergent. And even then, wouldn't it just be easier to switch everyone to something different?

I'd use the same pail too.