A mother-in-law is the chief. She thinks so a priori. It was she who gave birth to the son, and it was she who raised him. She was his head for quite a long time, but now she is deprived of this role. And the daughter-in-law knows nothing about how her beloved husband was brought up or what he liked when he was 3 years old… It means nothing to her! So, it largely depends on the mother whether her son will be happy or not. It depends on how much she interferes with his life, how altruistic she is in this issue and how much she tries to impose her viewpoint on the other family under the guise of “I just want to help”.
For a faithful mother-in-law it is important not to terrorize the newly-weds with her Orthodoxy. It will be enough just to be a decent person! Let me tell you how it was with my own son. My son Klim got married when he was 18. He grew up in church at an early age, while my daughter-in-law, Marina, was baptized in Orthodoxy, but that’s all. They were married in the Peter and Paul Cathedral, and it was their last day in the church. A usual life of young and loving spouses began, with its parties and other everyday worries… They came to church only on Pascha and the Nativity of Christ. But I personally was in the midst of my churching! Thank God, I was clever enough not to push them. There were some moments, for example, when I had to humble myself before my daughter-in-law in some household issues, and that was even more effective for me than any missionary preaching. By what right do you say what to do to someone who you do not know well, even if this person is 25 years younger than you? Who knows what is better at all?! Maybe she cannot iron his skirts perfectly well – she does not iron the sleeves on the inner side as they are supposed to be ironed – so what?! Your son is satisfied with what she does, so do not interfere. In Japan, people do not iron clothes at all!
However, the time came when Klim and Marina experienced a difficult moment in their life. They needed God… And I was already in the convent. Then they come to me for advice. To me and to Fr. Andrew, our spiritual father. It was their conscious step and their conscious coming to the Church.
So, you simply have to try to be friends with your daughter-in-law and to become closer to each other…