DP83TC811S-Q1: RGMII / SGMII use on one PCB

Hello, the question is the following:

a customer wants to use RGMII and SGMII on one board, just changing assembly by option.

From the PCB perspective, they want to do one PCB, which they can use either with RGMII or with SGMII as interface to the PHY.

1. The RGMII and SGMII signals are on the same IC pins. However in the SGMII version (DP83TC811S) there are less signals used. i.e. the TX_D2, TX_D3, TX_ER, RX_CLKM, RX_CLKP used not used in case of the 4-wire SGMII mode (RX and TX data only, no clock). Are these signal
   1.  floating
   2. or connected to ground
   3. just have the signals specified for RGMII?
2. Con these pins get configured by register settings to one of these behaviors ?
   Thanks and BR Ralf