How can we make my dads estate liable for my mothers estate?

Louisiana law is pretty different from other states so I would encourage you to talk to a lawyer there.  But I will give you some general information that I think, although am not sure, is true for all states.  It sounds like you and your siblings inherited some stocks, bonds, annuities, and property in 1998.  I'm not clear whether your dad had usufruct over those assets or whether he had usufruct just over the assets he inherited personally.  Your dad remarried at some point, and it sounds like he left everything to that wife.  Any assets that your dad inherited from your mom that were not encumbered by a trust, he was free to spend or transfer to his second wife.  Trust assets are usually not subject to probate process, but the the legal document that created the trust or his usufruct should include some language about who replaces your dad as trustee when he passes away.  That is the personl that you should be in contact with to determine whether you are entitled to any assets.  I'm not sure why you were in court or what your attorney failed to prove, but your rights and any actions you should or can take depend on the details of the usufruct, what assets are involved, what court action has taken place so far.  It honestly doesn't seem to me that you will be able to get sufficient legal guidance online.  I recommend speaking to another lawyer in LA who specializes in probate litigation.