How can a sum of money taken from a shop owned by several partners who are difficult to reach be estimated and delivered to them? Is it permissible to give it out as charity on their behalf?

A person must estimate the amount that clears their conscience and divide it according to each person's ownership share in the shop. If it is possible to deliver one's share to them, it is obligatory to do so unless they absolve you. It is not permissible to give it away as charity on their behalf as long as it is possible to deliver it to them. As for someone who cannot be reached, their share should be given away as charity on their behalf.