B001966 wrote:As far as I can understand the Aunts will is a seperate second settlement to the trust and as such does not contribute to the IHT issues of the father in law's estate and should be taxed seperatley.
Indeed. If there is a separate settlement for your Aunt, this has nothing to do with your father-in-law. The settlement into her trust can go in and come out again immediately, fairly simply. Your father-in-laws trust is completely separate and should be ignored. It will not be unusual for the same trustees and beneficiaries to be on several trusts. I'm not sure why you think they are linked. Perhaps there could be some missing detail in your question, which is always the risk on forums such as this.
I imagine her will established a discretionary trust as many do. A deed of variation could undo this, but as mentioned above, if your Aunt's settlement can be confirmed as being entirely separate from your father-in laws, everything under the nil rate band should be free of IHT. If as you state in your original question, free of income or capital gains, there should be no other taxes either.