Hi Anthony,
You still can sort by both dates on choice, but you will have to handle the sort manually(
custom sort), depending on which row of the header you have clicked. Same goes for, filtering and grouping. This however goes beyond the default capabilities and you will probably need to handle much of the interaction yourself.
Nicolas,
You can use the approach I posted in my first reply(use cell templates and HeaderCellTemplate).
Hope this helps.
Regards,
Nik
Telerik
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