it depends if the tax man accepts that the home you are living in has been deemed to be the main residence of the couple
if teh answer is yes - no tax
if the answer is no then - actually your wife property cannot have been her residence - and if it is then it dates from the time she moved in .... this year
actually you have time to deem - I think it can be done within two years of a change ....
but you should see an accountant with experience of tax affairs to do the negotiating. Your view should be the house you are in has clearly been your main residence at least up to the time of death of her father.