if i amend an apple ID password will messages still go to the device using the old one?

I have had 2 devices using the same Apple ID - one was my step daughters who went home and was receiving my messages on her ipad - resulting in her mum reading them. i have changed my ID and password on my iphone but do not have access to the ipad i have also changed the password on the original ID and need to know if this will have stopped messages going through to it?