"Necessary famly business" is the limiting buzz word for associating with family member who do not live in the same household. Typically a JW can decide by their own conscience what involves "necessary business" and will not risk DF for personal contact with a parent/child, however, they very likely would not be considered "without reproach" so as to qualify as a pioneer, MS, or elder. This may even apply to walking the mics etc. Seems that all originated in a 1981 or 1982 WT --- [dusting off CD] It is 09/15/1981 WT pg 26:
IN THE IMMEDIATE FAMILY CIRCLE
9 A person might become a Christian without others in that one’s family circle accepting the faith. For instance, a wife might be serving Jehovah, but her husband not. Despite that, she is still “one flesh” with her husband and is obliged to love and respect him. (Gen. 2:24; 1 Pet. 3:1-6) Or she might be married to a man who was a dedicated Christian but was later expelled from the congregation. Yet that would not end their marital ties; only death or a Scriptural divorce would do that.—1 Cor. 7:39; Matt. 19:9.
10 Similarly, if a relative, such as a parent, son or daughter, is disfellowshiped or has disassociated himself, blood and family ties remain. Does that mean, then, that in the family circle everything remains the same when one member is disfellowshiped? Definitely not.
11 A disfellowshiped person has been spiritually cut off from the congregation; the former spiritual ties have been completely severed. This is true even with respect to his relatives, including those within his immediate family circle. Thus, family members—while acknowledging family ties—will no longer have any spiritual fellowship with him.—1 Sam. 28:6; Prov. 15:8, 9.
12 That will mean changes in the spiritual fellowship that may have existed in the home. For example, if the husband is disfellowshiped, his wife and children will not be comfortable with him conducting a family Bible study or leading in Bible reading and prayer. If he wants to say a prayer, such as at mealtime, he has a right to do so in his own home. But they can silently offer their own prayers to God. (Prov. 28:9; Ps. 119:145, 146) What if a disfellowshiped person in the home wants to be present when the family reads the Bible together or has a Bible study? The others might let him be present to listen if he will not try to teach them or share his religious ideas.
13 If a minor child is disfellowshiped, the parents will still care for his physical needs and provide moral training and discipline. They would not conduct a Bible study directly with the child, with him participating. Yet this does not mean that he would not be required to sit in on the family study. And they might direct attention to parts of the Bible or Christian publications that contain counsel he needs. (Prov. 1:8-19; 6:20-22; 29:17; Eph. 6:4) They can have him accompany them to and sit with them at Christian meetings, hoping that he will take to heart Biblical counsel.
14 But what if a close relative, such as a son or a parent who does not live in the home, is disfellowshiped and subsequently wants to move back there? The family could decide what to do depending on the situation.
15 For example, a disfellowshiped parent may be sick or no longer able to care for himself financially or physically. The Christian children have a Scriptural and moral obligation to assist. (1 Tim. 5:8) Perhaps it seems necessary to bring the parent into the home, temporarily or permanently. Or it may appear advisable to arrange for care where there is medical personnel but where the parent would have to be visited. What is done may depend on factors such as the parent’s true needs, his attitude and the regard the head of the household has for the spiritual welfare of the household.
16 This could be true also with regard to a child who had left home but is now disfellowshiped or disassociated. Sometimes Christian parents have accepted back into the home for a time a disfellowshiped child who has become physically or emotionally ill. But in each case the parents can weigh the individual circumstances. Has a disfellowshiped son lived on his own, and is he now unable to do so? Or does he want to move back primarily because it would be an easier life? What about his morals and attitude? Will he bring “leaven” into the home?—Gal. 5:9.
17 In Jesus’ parable of the prodigal son, the father ran to meet and then accepted his returning son. The father, seeing the lad’s pitiful condition, responded with natural parental concern. We can note, though, that the son did not bring home harlots or come with a disposition to continue his sinful life in his father’s home. No, he expressed heartfelt repentance and evidently was determined to return to living a clean life.—Luke 15:11-32.
DISFELLOWSHIPED RELATIVES NOT LIVING AT HOME
18 The second situation that we need to consider is that involving a disfellowshiped or disassociated relative who is not in the immediate family circle or living at one’s home. Such a person is still related by blood or marriage, and so there may be some limited need to care for necessary family matters. Nonetheless, it is not as if he were living in the same home where contact and conversation could not be avoided. We should keep clearly in mind the Bible’s inspired direction: “Quit mixing in company with anyone called a brother that is a fornicator or a greedy person . . . , not even eating with such a man.”—1 Cor. 5:11.
19 Consequently, Christians related to such a disfellowshiped person living outside the home should strive to avoid needless association, even keeping business dealings to a minimum. The reasonableness of this course becomes apparent from reports of what has occurred where relatives have taken the mistaken view, ‘Though he is disfellowshiped, we are related and so can treat him the same as before.’ From one area comes this:
“One person who was disfellowshiped was related to about one third of the congregation. All of his relations continued to associate with him.”
And a highly respected Christian elder writes:
“In our area some disfellowshiped ones with large families have been met, as they enter the lobby of the Kingdom Hall, with a fanfare of backslapping and handshaking (even though the disfellowshiped one was known by them to be still living immorally). I feel a deep concern that those who have been disfellowshiped need to see that their course is hated by Jehovah and by his people and that they should feel a real need to become genuinely repentant. What will help these disfellowshiped ones to change when they are continually greeted by all in their large families who know of their practices?”
20 There must have been congregations in the first century where many were related. But when someone was disfellowshiped, were all the relatives to carry on as normal as long as they did not discuss Scriptural matters with the disfellowshiped person? No. Otherwise the congregation would not really be applying the command: “Remove the wicked man from among yourselves.”—1 Cor. 5:13.
21 Great care needs to be exercised that a person’s situation as a disfellowshiped sinner is neither overlooked nor minimized. As the sons of Korah well demonstrated, our chief loyalty must be to Jehovah and his theocratic arrangement. We can be sure that when we uphold his standards and prefer association with his organized people, rather than with wrongdoers, we will have his protection and blessing.—Ps. 84:10-12.
There are many more articles since then but the policy is basically the same other than they are increasing pressure to strictly limit any association with DFd relative outside the home. You son would get this pressure if he was baptized and did not reside with you.