Answered by Sayyidi Habib Umar bin Hafiz (may Allah protect him and benefit us by him).
What can be recited to increase harmony between family members and between husband and wife?
If possible, every family member should recite Ayat al-Kursi once and Surat al-Ikhlas three times every time they enter the house. This increases love between family members.
Reciting the following 41 times daily increases harmony between married couples and people in general:
لَقَدْ جَاءكُمْ رَسُولٌ مِّنْ أَنفُسِكُمْ عَزِيزٌ عَلَيْهِ مَا عَنِتُّمْ حَرِيصٌ عَلَيْكُم بِالْمُؤْمِنِينَ رَؤُوفٌ رَّحِيمٌ فَإِن تَوَلَّوْاْ فَقُلْ حَسْبِيَ اللَّهُ لا إِلَـهَ إِلاَّ هُوَ عَلَيْهِ تَوَكَّلْتُ وَهُوَ رَبُّ الْعَرْشِ الْعَظِيمِ
Laqad ja’akum rasulumin anfusikum ‘azizun ‘alayhi ma ‘anittum harisun ‘alaykum bi’lmu’minin ra’ufurrahim. Fa in tawallaw faqul hasbiyallahu la ilaha illa Hu ‘alayhi tawakkaltu wa huwa rabbu’l-‘arshi’-l-‘azim.
There has come to you a Messenger from among yourselves, grievous to whom is your burden, concerned (is he) for you; for the believers (he is) full of compassion, merciful. If they turn away say: ‘Allah is sufficient for me; there is no deity save He. On Him do I rely; He is the Lord of the Awesome Throne.’ (Al-Tawbah, 9:128-9)
Also recite in abundance:
رَبَّنَا هَبْ لَنَا مِنْ أَزْوَاجِنَا وَذُرِّيَّاتِنَا قُرَّةَ أَعْيُنٍ وَاجْعَلْنَا لِلْمُتَّقِينَ إِمَامًا
Rabbana hab lana min azwajina wa dhurriyyatina qurrata `ayun wa’ja’lna lil-muttaqin imama
Our Lord, grant us spouses and offspring who will be the comfort of our eyes, and make us an example to the people of taqwa. (Al-Furqan, 25:74)