romanchog,
I think Mary Jane gave you some excellent advice in how to help your younger child speak respectfully to his older siblings. There are many ways to show God's love and truth; it isn't only through words.
It is also wise to have a heart-to-heart with your daughter before she moves back into your house. I would counsel you to try and keep the "rules" to a minimun however; and keep them to some of the bigger issues. As other posters have mentioned we need to be careful what we call evil and to allow the Bible to guide these decisions. One of the biggest hindrances I see to allowing someone to really walk with Jesus is the dreadful "spirit of religion." By that, I mean a man-made system to rules and regulations that have the appearance of holiness/godliness but it denies the power thereof (2 Timothy 3:5).
Consider Paul's words to the Colossians:
If you have died with Christ to the elementary principles of the world, why, as if you were living in the world, do you submit yourself to decrees, such as, "Do not handle, do not taste, do not touch!" (which all refer to things destined to perish with use)-in accordance with the commandments and teachings of men? These are matters which have, to be sure, the appearance of wisdom in self-made religion and self-abasement and severe treatment of the body, but are of no value against fleshly indulgence. (2:20-23)
Notice that Paul considers all of this self-striving to only appear wise but it does nothing to affect the heart. We can make our own rules, but they do not change our hearts' motivations. We can hide away from activities that COULD lead to sin, but we never deal with the deep issues of our hearts and souls that would cause us to be attracted to those sins in the first place.
Contrast that lifestyle to freedom spoken of in Psalm 119:32:
I will run the way of thy commandments, when thou shalt enlarge my heart. (KJV)
I shall run the way of Your commandments, For You will enlarge my heart. (NAS)
I run in the path of your commands, for you have set my heart free. (NIV)
And then back to the New Testament: "It was for freedom that Christ set us free; therefore keep standing firm and do not be subject again to a yoke of slavery." (Galatians 5:1) The slavery that Paul speaks of here is a religious slavery. (And yes, he does tell us in verse 13 that freedom does not lead to sin, but to love.)
It may be helpful to ask your daughter what she expects your relationship to look like now and then to let her know your expectations as well. Because she is an adult now, she is now at a place where you will need to treat her more as a sister (in Christ?) than one of your little ones. Share your heart with her. As you open up the depths of your soul to her, it will allow her to see how Jesus lives in you. (In my life, the men who have impacted me the most are the ones that I've seen up close and personal and their lives speak volumes more than their words.)
It may also be helpful to talk beforehand about how you two will deal with the inevitable disagreements that you will have. Life does not turn out to be as cut and dried as we would like it to be. Paul acknowledges, that even in his own life there is a mixture of good and bad (Romans 7). If we could control everything, life would be rather dull and in reality we wouldn't need God at that point. So when these situations arise, have a game plan: will she leave the room, will you usher the little children into another room, etc. On that same note, it would seem to me, to be quite helpful to have a similar discussion with the little ones. One important lesson is to let them know that people can disagree on something and still love one another and remain respectful. Also, it is vitally important to let the little ones know that if you do need some distanct from your oldest daughter for a time, the time apart is so that you can eventually come back together even stronger than before.
Thank you for sharing about your children's lives. I can't imagine how difficult this season of life must be for you and your family. Hopefully the outlet you have here at SI to share your heart and soul will offer some measure of healing and encouragement for the journey.
Grace and peace,
Matthew