DDR3 SDRAM UniPHY problem with parameters

Hi.

I start to develop a new project, were i need to drive DDR3 chip. The external data bus I’d like set is 48 bit, in order to use 3 chip of DDR3 with 16 bit data each. So I’d like put 16 bit DQ group, but it is only possible set 4 or 8 bit. The number of chip select I’d like set is 3, but it is only selectable 1,2 or 4.

There is a method for set the right parameter for my project?