HI
please try to look up the website link below as it explains the new Individual budgets and by creating a number of funding streams the people you care for could live independantly from yourselves in small group homes. Its not quite here yet but will be soon.
The general rule is to get an independant advocate so your cared for person has a unbiased voice and stand firm in your request that as an adult they wish to now live independantly and living with you is no longer an option.
http://individualbudgets.csip.org.uk/index.jsp
good luck
sally