With the destruction of the traditional extended family and the migration of Muslims from the village to the city or abroad, we are losing intimacy with family and with our kin - kinship relations are weakening or deteriorating without support.
Every family has some family members with whom there are problems, but this should not be a barrier to your relationship. You are strengthening family ties for God's sake!
Remember the hadith of the Prophet Muhammad (peace be upon himpeace and blessings be upon him) who said: "Whoever responds kindly to those relatives who treat him well is not considered to have fulfilled his duty towards them. It is said that only he who continues to treat them well, even though they have ended all relations with him, has fulfilled his duty" (Bukhari).
If you haven't been in touch for a long time, try to arrange a meeting through an older family member. Even a virtual meeting via video chat would be a small victory. If the relatives live in the same town, you can invite them to an iftar. If the older generation is reluctant to meet because of some family differences, try to organise a meeting among the young people. And at the iftar you can discuss how to settle family disputes.
Possibly past grievances are related to money matters - for example, if someone in your family has refused to help you in your time of need. Allah gives clear instructions that alms and zakat are meant for our relatives as well as the poor and needy. In fact, the scientists emphasise that in charity we should give priority first to those closest to us and then to the rest of the Ummah. There are practical ways to do this, such as giving Sadaqah to a poor relative through an older family member, or contributing to a large expense for one of the relatives, such as paying for a child's school fees or a medical surgery.
Perhaps there are people in your family that you have never met at all, that you may have heard something about from your parents and other older relatives. There is now an opportunity for you to reach out to the families of these people. If they live far away, write to them. Look for someone from their family on social media - you may be able to get in touch with their children and younger family members. The more you find your relatives, even if they are distant and long forgotten, the better, the more credit you will have for keeping in touch.
Let us not allow shaitan or our busy-ness to take away this benefit from us, especially in the month of Ramadan. It is enough that Allah has promised to maintain intimacy with those who are close to their kin!