WMS. How to create a new parent (root) group

ThinOS Group Parents are special groups.  They are "Select Group" objects. 

https://dl.dell.com/content/manual22857312-dell-thinos-2402-administrator-s-guide.pdf?language=en-us

Page 163

Select groups are to allow your users to select between different brokers or environments.  As such they are only allowed to be created at the root of the tree under Global Policy.  

You do NOT need to create a Select group for basic ThinOS policies. 

Yes I want to setup a totally different ThinOS policy. Don't want to have to disable/reverse inherited policies.

The doc says :

1 Log in to the Wyse Management Suite server.
2. On the Groups & Configs page, click the Default Device Policy Group option.
3. Click  +

I can't do that. "+" is greyed out. Maybe this is a limitation of WMS free ?

Select groups are a pro only feature, but it doesn't sound like you are trying to do that, and there arent limits on groups in Std (Free).   Can you share a picture of what you are trying to do?

I want to add a group like TMIS9. But the interface only let me create sub-group of TMIS9

checkbox "This is a Parent" is greyed out

Now I see why.   It looks like you have renamed the default group, "Default Device Policy Group" to "TMIS9" (Which I did not even know you could do).    Even though you renamed it, the same rules apply.  Your device groups start under the parent group, you cannot create a new parent group.  

My advice, 

Treat that top level group, which you called TMIS9 as your top level group, don't attach any policies or devices directly to it (Setting anything at that level ensures everyone must get those settings, which is usually problematic. 

Create a new subgroup under there, this would be your base group.  I usually don't advise putting any settings or devices at that level either.  begin building out subgroups and policies underneath there. depending on how you need to differentiate them (Different brokers, different apps, different timezones, different business units).   

This will give you the most flexibility.