The life estate is not an asset that can be passed from heir to heir. Only the named beneficiaries are those recipients, in this case the son(s). The life estate doesn't pass to the grandchildren, it passes to the remainder man or men, which would also be named in the will. In other words, after the brothers died there should not be a life estate.

You need to contact an attorney to get this sorted out and get the deed handled, or, more likely, the executor of the estate. This really isn't a DIY project.