I think you may be right and that William Leander Gash and William Gash have been conflated. There is a FindAGrave for William Leander Gash with a tombstone picture which has a list of children on the stone and the list of children is totally different than the ones listed here on WikiTree.
I think what you need to do is to detach William Leander Gash from all the children listed here on WikiTree, then create a new William Gash (Your William Gash) to attach to them as father. Mary Gash's profile here has no profile manager, so you can adopt it and any other of the children's profiles who also have no profile manager. They have little in the way of decipherable sources, so you can add your sources and information which will greatly improve them.
To detach William Leander Gash from the children, click on the edit tab on his bio, on the right beneath the list of children is a link "add/remove children." Click on it. Scroll down on the next page to Section II to remove all the children and submit your changes.
