Thomas, if I'm understanding your dilemma correctly, it seems you say that you and a first cousin are on FTDNA, but on Wikitree there is no relationship showing. This occurs when you each haven't completed a tree up to your common ancestor, or one of you has entered wrong information on an ancestor, or you both have created profiles for common ancestors (thus having duplicates). If both you and your first cousin are on Wikitree and are first cousins, then it should be only a couple generations back to your common ancestor. Look at each profile and see where the problem occurs. If there are duplicate profiles, then you need to propose a merge.