Manage GPOs in one console in two forests without trust established

Question

I have two forests that have no trust between them - and can't because of security reasons. I need to manage both forests from dedicated PC with one console that can manage GPOs in both forests at once = in one console window. I have credentials for both forests, just can't connect them. I am struggling mightily to find any reference how to do this without trust or someone who already sucesfully did this?