If someone needs to consolidate their FFEL or Perkins, or even Direct loans on different timelines for forgiveness, we normally assist by walking someone through this during a phone call or zoom strategy session. That way it is done and immediate. There are times where a paper application is needed however and here are the addresses for this (send certified return receipt or FedEx/UPS with tracking number):
Aidvantage
PO Box 300005
Greenville, TX 75403-3005
EdFinancial
C/O Aidvantage
PO Box 300008
Greenville, TX 75403-3008
MOHELA
C/O Aidvantage
PO BOX 300006
Greenville, TX 75403-3006
Nelnet
PO Box 82658
Lincoln, NE 68501-2658