First refusal

Another problem .My mother died 5 years ago not leaving a will so house left to my sister and I.I have paid most of bills and done all maintenance since then.My sister has now died and her children have said they are going to sell the property for as much as they can get.We have put in a claim(not invited to) for 50 per cent of bills and our time and energy.They have had it valued,we can afford to buy them out do we automatically get first refusal to buy their share?Thank you for any replies.

First refusal