How to connect four LSM9DS1 on a common SPI bus.

[TAnde.7]

I need to connect four LSM9DS1 on a common SPI bus. (I2C won't work here---resources are not available on the host microcontroller.)

I'm having a hard time getting the following from the datasheets, and hoping maybe someone with experience with these chips can give me some pointers:

• In 4 wire SPI mode, do SDO_M and SDO_A/G assume a tristate/high-impedance state when their respective chip selects are not asserted?
• In 3 wire SPI mode, does SDA/SDI/SDO become tri-state/high-impedance when a chip select is not asserted?
• Is there any way to avoid needing both chip selects, and somehow tie these together for each chip, selecting whether you are talking to the A/G or Magnetometer via a register setting?

Thanks!

Tyler