how can I set different sample rate in a same daq session (ni hardware)

Hallo everybody. I would like to manage different daq board (ni hardware), for example a NI 9213 for thermocouples and a 9205 for some fast audio signal. I'm using the data acquisition toolbox via matlab 2014a release. As i learned on the help first of all I clear all eventually running daq processes with

if (~isempty(daqfind))
    stop(daqfind)
end

then I create a daq session wit the command:

DAQ_session = daq.createSession('ni');

then I add mi ai channels with the usual command

DAQ_session.addAnalogInputChannel(dev, ch, meas_type);

While trying to set my desired sample rate of each channel I "discovered" (and confirmed via matlab help) I cannot set a specific sample rate for each channel because the command

DAQ_session.Rate = XXX;

works for the whole daq session object (there is no method for object of type Channels).

How can i bypass this problem? I'm pritty sure my problem is not so unusual so I think Mathworks surely has a ready solution... but I've not yet found anything!

Thanks for your help in advance.

Eddy.