Sounds awful that this decision is the only one to be made for her. She will not benefit in her recovery by living with you, temporarily. But it sounds like 'what's done is done'. My only recommendation would be to get your butt to an alanon meeting... and more importantly be vigilant as to how this will affect your child.
Obviously you can set your own boundaries.. and that depends on what you're willing to live with. One of my boundaries would be not to allow an alcoholc to live in my home or with my children..
Some of yours might be the plan you already have mentioned.. for her to follow her aftercare plan (what rehab DOESNT recommend sober living?? that's bizarre that it's not in her discharge orders). For her to remain sober. For her to be productive in her life and in your home. A timeline for her moving out and on with her life. A recovery plan. A sponsor. Course, she may come there and get stinkin' drunk every day, as that's also her choice. And if she doesn't follow what you are willing/aren't willing to live with, to take ACTION immediately... or don't, and enable her further.
Quite an unfortunate situation, for all involved.