Is the agency of a foreign company considered part of the capital or assets that can be sold when liquidating a company, and is it permissible for the son to be a partner in it without disadvantaging the heirs?

Regarding a commercial agency: If it was concluded with the father's company as a legal entity, then it is part of the company's rights and assets and is inherited from him, like all his inherited rights, by each heir according to their Shariah-prescribed share. Similarly, if the father had purchased the agency from the company, he is entitled to sell it. However, if the agency is specific to the agent as an ordinary person, without permission to transfer or sell it, then he cannot assign it to others, and the agency becomes void upon the agent's death.