You can only do what you want to do with your father's cooperation and assistance --he would have to obtain either a stipulation with your mother for your sister to change primary households, or to file a motion to alter primary custody. See:

http://willicklawgroup.com/child-custody-and-visitation/

One other alternative would be for you to seek a guardianship and have your sister live with you, wherever you are off to for college. See:

http://willicklawgroup.com/guardianship/

But that is a substantial burden to be putting on an 18-year-old who should be trying to figure out her own life in transition to adulthood.

To get knowledge of "how these things work," start with the explanation and materials posted on the website referenced above. Then have a talk with your father. Then your mother. Then consult an attorney well versed in family law to make whatever you have come up with happen.

You can only do what you want to do with your father's cooperation and assistance --he would have to obtain either a stipulation with your mother for your sister to change primary households, or to file a motion to alter primary custody. See:

http://willicklawgroup.com/child-custody-and-visitation/

One other alternative would be for you to seek a guardianship and have your sister live with you, wherever you are off to for college. See:

http://willicklawgroup.com/guardianship/

But that is a substantial burden to be putting on an 18-year-old who should be trying to figure out her own life in transition to adulthood.

To get knowledge of "how these things work," start with the explanation and materials posted on the website referenced above. Then have a talk with your father. Then your mother. Then consult an attorney well versed in family law to make whatever you have come up with happen.