I asked your question to Jim Stephens who is in charge of the Blessing Family Department in the US. Below is the answer. It includes a letter from Rev. Phillip Schanker as well.
Father does NOT want 1st Gen and 2nd Gen to marry, but there has been some confusion.
Please read about it below and let me know if you have questions.
LETTER TO: BFD Representatives and BFD National Ministry Coordinators
Clarification about matching Second Generation to First Generation.
There has been some confusion about whether Second Generation can be matched to First Generation. Father did it himself a couple years ago in a special case of older BC girls who did not have any prospects of finding a match. With their permission, Father matched them to pure Jacob Children.
Because of a misunderstanding, several high level leaders announced that Second Generation could now be matched to First Generation. That is NOT correct. Only Father can do it and only under very special circumstances.
Unfortunately, we are still trying to correct many misunderstandings by members who heard those mistaken announcements. In addition to that, the book that my wife and I have been promoting by Dr. Yoshiko Masuda with many of Father's words about Husband-wife relationships also contains this error. In Vol. 2 (green one), on page 10, this misunderstanding is repeated. The book exists only in Japanese and all Japanese members in Japan were told of the correction.
However, many Japanese members in America who are reading this book probably did not hear about the correction. They need to be told and I would like to request your help in spreading this announcement among your Japanese members.
Below are two clarifications. One is from the author of the book, Dr. Masuda. A second explanation is from Rev. Phillip Schanker.
Letter by Rev. Phillip Schanker
To Whom It May Concern:
To the best of my knowledge Father has, on 2 or perhaps 3 occasions, made a special matching between 1st and 2nd Gen. partners. All of them were unique and providential, as in the one case I know about: when TF invited representatives of the Korean STF to Yeosu for a day of fishing, etc., a Japanese brother was lost in a boating accident. Thinking the brother had drowned, all were surprised to find him hours later in the air-filled hull of the capsized boat, waiting for rescue. TF was relieved and inspired, and declared the event a meaningful providential occurrence. He matched this brother during the celebration and his talk. One was 2nd gen, the other 1st. Also prior to the Dec. 29, 2005 "Gyocha" Blessing, TF mentioned that if no match could be found for any older 2nd Gen candidate, TF would consider matching them to 1st gen., if they were willing. In this case it seems he was concerned to make sure that all 2nd gen. would have a match. He made no such couple this time, but one can imagine that this situation will arise again as 2nd Gen get older.
It is clear that in each case like this, TF was exercising his authority for some special reason. I am not aware that he has extended that authority to allow anyone else to match 1st and 2nd Gen. He clearly encourages Blessed Children to contribute what they have to offer to the renewal of God's lineage, preferring pure 2nd gen. be matched to pure 2nd gen. rather than to 1st Gen or Fallen 2nd Gen.
For Fallen 2nd gen. who have restored their faith, TF prefers they be matched with the same category rather than EITHER pure 2nd gen. OR 1st gen.
Some parents, more concerned with the happiness and desire of their children than with lineage issues, have allowed or approved a 1st - 2nd gen. match & Blessing between their children who may love each other and request it. I am not aware whether or not approval from TP has been sought or granted in any of these cases. I know most have been without permission, and doubt that any have been allowed. Certainly, one day the barrier between 1st and 2nd Generation may be eliminated, as well as between 2nd and 3rd, 3rd and 4th, etc. I don't believe that day has come yet.
Certainly many 2nd Gen. cannot comprehend or relate to the value of their pure lineage, or how important it is to TP for the restoration of True Love & God's sovereignty. When a 2nd gen falls in love with and marries a first gen. outside the Blessing, they lose their position as 2nd gen. I assume that when 1st & 2nd gen couples were matched by TF (2 or 3 cases, as I said) they are lifted to the position of 2nd Gen. by God's grace & TP's authority, but I am not sure. Certainly most 2nd gen would not want to be matched by TF to 1st Gen. if it meant losing their precious and important position, nor is it likely that TF would do such a thing. There have been some 2nd gen. matched with a 1st gen. with their parents approval only, and allowed to participate in the Blessing, though the idea is strongly discouraged by some BFD's & leaders, and not allowed by many others. In these cases, the couple must accept that their position is First Gen and that they must go the restoration course of First Gen (i.e. Holy Wine, Indemnity Stick Ceremony, Blessing, 40-Day Separation, and 3-Day Ceremony). Also their children will walk the course of 2nd Gen. not 3rd Gen.
I hope this understanding is helpful. As you pray about these things please remember and value the precious seed of your children's pure lineage, and of all the sacrifices of 6000 years, from Abel -to-Jesus-to-True Parents that it took to realize it. It is a profound and serious consideration whether to "spill that seed" for any reason.
Love and prayer, Rev. Phillip Schanker