The treatment depends on the circumstances of each individual case and is impossible to anticipate in any given case without a full assessment of the facts of that case.
If the sums involved are material, you should seek appropriate legal or tax advice.
Ok I thought it would have been more black and white than that. If it helps the disposer would be the sole owner of the properties at the time of passing?
Suffice to say there have been authoritative books written on CAT that devote a surprising number of pages of small text to the various permutations of how the valuation date is to be determined according to circumstances.
The information here and any further guidance documentation linked from that page might help but may not be a substitute for professional advice as per @T McGibney's posts...