Who is liable for Capital Gains Tax on proceeds of a house sale?

My father died 12 years ago and in his will he left his half of the house (bungalow) equally to his 5 children. The bungalow has just been sold, half going to my mother, who is in a care home and half to the 5 children. My brother and I are executors and trustees of his will. When he died the property was registered with the Land Registry with the proprietors being my mother and myself and my brother. The other 3 children were not mentioned on the document. Now we have received the proceeds of the sale, we have been unable to find a definitive answer to this question. Do we split the proceeds equally 5 ways to each child who are then individually responsible for their own capital gains or are my brother and I liable to pay the Capital Gains Tax and then distribute the net proceeds?

Hi,
As the will specifies the 5 children, each child needs to report their share of the gain.
Thank you.

Thank you for your help.