Telnet-1,
Only 3 of the radios of an MSR4000 can be on the 5GHz band. 1 radio has to be on the 2.4GHz band.
In addition, for your application you must use 20MHz channels not 40MHz channels. And the channels must skip one (e.g. center frequences at least 40MHz separated).
E.g. channels 147, 157 and 165 can be used in 20MHz mode. Each supporting separate MST200s downstream on their own channels.
Also, you must use directional antennas in this configuration, you cannot use 3 sets of omni antennas for instance. But this shouldnt be an issue as sectored deployments are going to use panel antennas anyway.
Generally, you want to use the narrowest horizontal beamwidth antenna you can in each sector to achieve the highest gain. So you want to use either the ANT-2X2-D607 or ANT-2X2-5614 depending on how far apart in degrees your MST200s are in that sector.
Each MSR/MST radio can support a maximum of 6 children.
hope that helps.