Group-Group dynamically devices, Max group number


I am testing now the volumio 3 multi room capability. I have two question.
My question is there any possibility to control by API or something else, the grouping of the devices?
If I have to write some scripts on the devices, is not a problem.

For example I have 10 devices. Sometimes I need to use them together, in one big group.
But sometimes I just need to play 2 or 3 devices together. It would be good to switch between group scenarios, but now there is no option for it.

My second question is, I can’t find the info about, which is the maximum device number in a group?


Not sure how to make subgroups, but the maximum numer of devices is 6.