My idea is to connet a small subpanel to this pullout block. The fuses you install in it would be the mains that would be feeding it. If the pullout has the smaller cartridge fuses, use two 30 amp fuses as mains to feed the subpanel. If they are the larger clips, install two 40 amp fuses. Use a subpanel with four circuit spaces, and run your two new circuits from this subpanel. If you are running circuits for a washer and a bathroom, they should each be 20 amp with no other lights and appliances on them. You would also have two more spaces available for light loaded circuits if they are needed later on.