I was sent a recent recording of Rav Reuven Feinstein,shlita regarding kiruv and mixed couples. He explicitly says that it is prohibited to advertise and promote seminars to attract mixed couples to come with the hope that they will eventually convert. He says that is only permitted to strengthen those couples that come on their own with a genuine interest to learn more about Judaism and without an awareness that mixed marriages are prohibited. Only such couples who are interested lshem shamayim are to be converted while those who know that intermarriage is wrong are to be rejected. He says it is not only his view but it is one Rav Eliashiv, shlita, expressed when they asked him what was permitted. Rav Reuven's view is the one I have long defended as normative against R' Tropper and his representative Roni - while they defended the view which Rav Reuven explicity rejects on this recording. Below is an example of EJF's advertisement for attracting mixed couples to a seminar - exactly that which Rav Reuven says on this recording is clearly prohibited.
Hidabroot Org BNRImgDetail ASP Qs3czfsi