Is it permissible for the deceased's sisters to hide the house documents and delay their brother in selling it, in order to preserve the right of his two daughters from his first wife, and what is the ruling on the two daughters taking a share of the house's price if it is sold?

You do not have the right to prevent your brother from disposing of his house. The writing over of the house to his daughters is, in reality, a gift (hiba), and the father has the right to revoke it, based on the saying of the Messenger of Allah, peace and blessings be upon him: "It is not permissible for anyone to give a gift and then take it back, except for a father regarding what he gives to his child." There are four conditions for revoking a gift given to a child: the gift must remain in the child's possession and control, no rights of others should be attached to it, and it should not have increased with an attached increase. If your brother sells the house, his daughters have no right to its price, but the father may donate to them if he treats them equally.