I have 2 indoor cats.
Tilly came to us about 3 weeks ago from a friend who wasn't really looking after her properly 
She settled in well and gets on with my existing cat as well as can be expected (they play, but fight occasionally, they follow each other around, neither one has hurt the other, they share food bowls and litter trays even though I bought new ones for Tilly)
Anyway, Tilly knows where the litter tray is, she has been using it, but she is also pooing on the floor next to the tray and she pooed over the bottom of my living room curtains.
I get up this morning and she has peed on my bed!
What can I do to help her exclusively use the litter tray?
I did take the 2nd litter tray away because both cats were using both tray's but maybe I should put it back?
her poo is also really runny. I put it down to the stress of the move, but it's been over 3 weeks now and I expected to see signs of it getting better.