A connector system includes an upper electrical connector having a housing that defines an open bottomed cavity defining a cavity envelope and that defines a mating interface for a mating connector. The upper electrical connector further has contacts mounted to the housing and extending along the mating interface. The connector system includes a first lower electrical connector mountable to a circuit board that has a first outer envelope adapted for fitting in the cavity envelope, and a second lower electrical connector mountable to a circuit board that has a second outer envelope adapted for fitting in the cavity envelope. The upper electrical connector is separately mountable to the circuit board over each of the first lower electrical connector and the second lower electrical connector. Optionally, the upper electrical connector may be mountable over only one of the first lower electrical connector and the second lower electrical connector at a time.