Switching to Simple Practice

My group is currently switching to Simple Practice from another EHR.  We are currently set up to electronically submit claims and to receive ERA's through this other software.  I know that we need to enroll with the various insurance companies to do this through Simple Practice.  My question is, what happens to the ERA's we previously submitted through our old EHR/Clearninghouse for sessions that happened before we switched once everything is set up through Simple Practice?