Move them all into the big coop after they have settled in their usual coops for the night. Remove the small coops. They'll be a bit puzzled the following night, but once they realise there is only one place to settle at night, they should go there. If you think this might fail, and the new coop has sufficient light, put food and water in there and confine them for 24 hours.
Guinea fowl & a lot of surplus poultry equipment.