Frank,
Unless I'm misinterpreting the feature that you're seeking to use, as far as I'm aware, Multidrums are only available on the Drums track. Realdrums are not able to be loaded onto tracks other than the Drum track unless a specific number of bars of a drum track has been converted to an acidized loop.
I include the below in my post just in case it's useful information.
Regards,
Noel
IMAGE 1 (How to access the Multidrums)
1. Right-click somewhere in the region I've called #1.
2. Select Multidrums (#2).
3. Select one of the options shown by #3.
IMAGE 2 (Adding multiple lots of Realdrums)
1. Enable Multidrums (#1) in the dialogue box that pops up.
2. Enable the individual tracks for the added drums.
3. Choose the drums you wish to add (buttons #3).
4. The dB offset (#4) allows one to balance the volume of the added drums against the existing percussion. Negative values will lower the volume and positive values will raise the volume.
Description: IMAGE 1 - How to access Multidrums (BIAB 2017)
Description: IMAGE 2 - Multidrums settings