As per (UG482) v1.8, only XC7A200T-FFG1156 can be sourced by an adjacent quad's GT reference clock.
When the advanced clocking option is selected, the EAST, WEST REFCLK clock inputs to the PLL common are not brought out.
The clock forwarding option for an XC7A200T-FFG1156 device is not currently supported by the transceiver wizard.
If you are dynamic switching or sharing, you will need to manually bring the reference clock ports to the top and connect them (and drive the PLLREFCLKSEL) appropriately as per (UG482) guidelines.
02/09/2016 - Initial Release