need help urently

I think that you need a lawyer to sort all this out.

Yes Gala is right.You must get a lawyer preferably a specialist too, there is absolutely no way you'll ever see a euro without one.In any case you're looking at a very long affair (5-7 years at worst) but if you don't start proceedings immediately you may even start to lose some of your rights !,good luck. 

 Technically you should have paid toward the renovation costs, but you should have also had your share of the rental income and a rent for the house.   unfortunately you will need a lawyer, and it may end up costing more than your 1/8 share of the property.  You should dig your heels in and explain that if they want contributions for the renovations, (which have added to the market value of the property) you want back rent.  The value of your share should be estimated by a professional and include the renovated value whether you paid for it or not.  They will be buying what the property is worth today.  However, an 1/8 share of a house does not have a high value! 

I agree with Ram, get a proper valuation and then you will know whether it is worth all the trouble and money it is going to cost. Are the sisters single and are there more heirs who support their attitude? Is there a will? A share of only 1/8 makes me think that there are other heirs involved as well.

Thanks to everyone for the advice given. however i must explain things further so perhaps they can be a better understanding of the situation. When my father died and we filled in the declaration of succession the lands went throudh ok but we discovered that the sisters had taken my fathers name off the deeds. We had already engaged a lawyer and we pursued the matter through the italian courts and the judge  looked at all the evidence and ordered the sisters to return the share of the house to us as although they had been given the right to live there, by a scrittura privata ,they had no right to sole ownership of the property.  They had all of the court costs to pay since they lost.                            Since then they offered to buy our share of the house and the undiveded lands that remained. We did get a valuation for the house and the lands but the sisters insist  that they are entitled to take the cost of rennovating the house off the maket value off the house. At no time was my father informed or asked for a contribution and in fact we knew nothing of the work till it came to light till after his death. Surely since the sisters lived there whatever they did it was for their own comfort and since they lived there without paying any rent to my father we are entiteled to the full market value. They also  had rented and worked the lands over the years and from that received an income which my father did not receive any portion of.    Any thoughts on this would be welcome.

You say you there is a carta privata giving them the right to live in the house - is it a right of occupation or a right of usufrutto? Was there a peppercorn rent?   I would think that they will be responsible for all the renovation costs, given that your father as owner was never informed of the works or asked as part owner to contribute or give his assent.  However, in court you would have to prove that he/you never knew of the renovation works, and not knowing is much more difficult to prove than knowing if you see what I mean.    Its a classic Italian story, and a lawyer would have a field day, and certainly go out to get back rent for the land from the sisters.    If they had/have the house in usufrutto, they will legally be responsible for all costs until their deaths, though technically in the event of a sale the person who gives the right of usufrutto must detract 'improvements to the bene' from the sale price if the usufruttuario buys.  So its not going to be easy.  Back rent for the land is easier to sort out.  

 So your grandmother had usufrutto and gave right of abitazione to your aunts - the usufrutto expired with the death of your grandmother, as did the right of abitazione except that they had been there for more than 20 years.  If the improvements were done during the lifetime of your grandmother than any rights would also expire with the expiration of the usufrutto.   Taking your fathers share of the property under usucapione wouldnt work because the owner exists and was traceable (and known to the others).  To my mind you are not responsible for the improvements and should not have to pay - nobody knows what agreement, if any, was reached between the sisters and the usufruttuario (your grandmother) for the financing of the work.  However, you will still need a lawyer to sort it out,   When the brother died the procura ceased and all matters should have been related back to your father, which they obviously weren't - so you also have a right to his share of the rent of the land for that period, (at least from 1992 onwards).   See what Charlotte Oliver says - she's the guru!