c# - WPF - DataGrid limit row multiselect depending on first selection -

curently have datagrid displays custom class items don't matter here. i'm using custom datagrid control inherits datagrid. because i'm using mvvm model , needed implement bindable selecteditemslist.

i've implemented collectionviewsource can group items desires.

now problem i'm having need limit users selection options after first item selected..

since don't want allow user selecting multiple rows in different data groups. there elegant way? because idea not ideal... (when selection occured test if every element has specific property of same type).

i've tried on google, untill couldn't find answers or maybe english knowledge limited "ask" right question allfriendly google.