Is it considered maintaining kinship ties to inquire about relatives through their children or to give charity on their behalf, in cases where direct communication or visiting them is difficult due to distance or not knowing their whereabouts?

The principle of Sharia is that Allah does not burden a soul beyond its capacity. As long as you are unable to reach your relatives or communicate with them, there is no sin upon you. It is sufficient for you to inquire about them through their family members. If it is possible to communicate with them without informing your father, should he become angry about it, then do so, while advising him gently and explaining the virtue of maintaining kinship ties. As for giving charity on behalf of a living person, there is a difference of opinion among scholars regarding it.