R610 memory upgrade

Hi,

We'd like to upgrade the memory of a R610 server (dual processor), at the moment we have this configuration:

A1 (2G) - A4 (2G) | B1 (2G) - B3 (2G)
A2 (2G) - A5 (2G) | B2 (2G) - B5 (2G)
A3 (2G) - A6 (2G) | B3 (2G) - B6 (2G)

We need to add 4 modules of 8Gb, what could be the best configuration for us? (obviously we can remove some 2Gb modules). We can afford a non-optimal configuration (avoiding to press F1 on non optimal configurations).

We've make some test reading the Dell documentation, but we only has been able to work this configuration:

A1 (8G) - A4 ( ) | B1 (8G) - B3 ( )
A2 (8G) - A5 ( ) | B2 (8G) - B5 ( )
A3 ( ) - A6 ( ) | B3 ( ) - B6 ( )

Do we have any other option to populate some of the free slots with 2Gb modules?

Thanks!