Inheritance

I have a big headache of a problem with IHT, here is my situation: My father died in the UK nearly 2 years ago, he owned a French Villa but lived and died in the UK, with only a UK Will that excluded the French Villa from it. I have a half brother and sister and in the UK Will they had big shares of this where as I only received a cash legacy meaning I do not have to pay any UK IHT on that amount. I then inherited a third of the French Villa and paid all my IHT taxes and fees in France and have received that money. I am not really on speaking terms with any of the other family as I never knew them growing up. Now I always believed that the double taxation treaty would come into play and the 40% of the French Villa Inheritance Tax would be paid by the UK estate and they can offset the 3 childrens tax paid in France. The problem is my fathers estate solicitors and excecutors want me to pay the 40% tax (minus the French taxed paid), but my argument is that as I do not benefit from the UK IHT tax relief why should I have to pay the UK tax personally its part of the estaes global assets? Now the solicitors and executors are trying to take the French Villa outside of the UK Estate and treat it seperateley as the UK Will said excluding the French Villa. Now my UK solicitor who is French and been advising me and my fathers estate solicitors are awaiting a final decision from the Inland Revenue but this seems to be a grey area as this is a unique case. My argument is sureley if it gets taken out of the UK estate and treated seperateley surely the 3 children involved should have full IHT relief making the tax to pay minimal? Any help, advice or views would be very helpful as if I do not agree with Inland Revenue decision I may have to appeal, and all this seems to be happening because the UK estate excecutors do not like the fact I will not have to pay UK IHT tax.