MMC interfaces on AM335x

Hello,

I am working on a port of U-Boot to a custom hardware platform based on the TI AM3354. According to the schematics from the hardware design company, the AM3354 has a 4bit MMC interface (MMC0) which has been connected to a uSD card connector.
There is a second interface (8bit) connected to GPMC signals which is connected to a Micron eMMC device labelled as MMC1.

U-Boot and the Linux kernel will be stored in a separate SPI flash device and the eMMC card will hold the root file system and the uSD card for removable storage. Am I correct in thinking that if U-Boot boots with no uSD card installed the eMMC device will be accessed as device 0 e.g.

U-Boot> fatload mmc 0 ...

but if it boots with a uSD card fitted then the eMMC device will be device 1, e.g.

U-Boot> fatload mmc 1 ...

Is there any way to force U-Boot always to map the eMMC device as device 0?

Thanks,

Andy.