Hi
I have recently got a new patio door and also got a cat flap installed hoping to get rid of the litter trays for my two one year old kitties.
It took a while for them to get used to it but they are fine now 
Anyway DS (5) came downstairs before me the other day in the morning and said there was a ginger cat in our house. This ginger cat has been terrorising both of my cats (one in particular)
I went downstairs at 4am this morning (don't ask!!) and there was the ginger cat curled up on my sofa
[the nerve emoticon] and my two nowhere to be seen.
Once ginger cat ran out my two appeared (I suspect they had been scared off).
Is there anyway I can prevent this happening again??
Can I shut my two cats in overnight without litter tray say from 11pm to 7am??
V reluctant to re-instate litter tray...
TIA