Welcome and sorry to hear about the loss of your dad a year isn't long and you will be feeling it even more now your brother has fallen out with you.Sometimes this does happen in families when a key member is lost,I know a family where the dad died and three siblings didn't speak for years,In the end it was a niece getting married who laid down the law and said they either made up or didn't get invited and that sorted it out.Not knowing you or your brother or why he fell out with you I can't really judge,but it does seem unfair on the children.Perhaps give it a while then ask for a truce at least for things like birthday parties so they don't lose contact.Meanwhile if we can help you with support over grieving for your dad we will be here for you.