Shalom ,  The Best way to approach the subject is by focusing on the environment that you would like to have for your children growing up and the unique opportunities that Israel would offer.  Key to your husbands perspective would be access to his children.  Since spiritually the mother is the key to influencing and educating the kids that your husband has fathered they will still have a strong link to him but frequently have preferences  for the mother even if he sees and spends quality time with them daily. In the Torah ,Sarah understanding the differences between yishmael  and yitzhak  led to her advising Avraham  to expel yishmael and Hagar.  The verse relates that Avraham heard Sarah.  This is what should be emphasized to your husband.  Recognize that your superior instincts aren’t always shared by your husband and that his desire is to manage both being available to his kids and to his eventual dreams of living in Israel. Ultimately you shouldn’t make it a question of doing whats right for yourself and your daughter vs doing what is right for his other children but really what is right for everyone as a man is to cleave to his wife and that is you.  In the long run his other children will actually benefit spiritually from him developing spiritually in Israel.     best wishes  —-R.Yosef Karpman