Is it permissible for someone entrusted with distributing alms to change the beneficiaries from previously designated poor and needy individuals to others who are more impoverished, without informing the donor?

If the donors specify certain poor people for their alms, then it is not permissible to give them to others. However, if they leave it to your discretion, then it is permissible to give all or some of them to other poor people. The ruling on transferring Zakat from one country to another is clarified in Fatwa no. 36050.