We're using v2.0.0.0 Self Service.

I have a MasterProjects table with child SubProjects. I GetMulti on a MasterProjects collection which has been dragged onto the form at design time. I've pointed a Gridex control at the SubProjects as a datasource.

This works fine, except to sort the children I have to do that at design time too.

Is there any way to get all the parents with the children sorted at runtime?

If you mean sorting the children at the database (fetching them sorted). Then use a prefetchPath to fetch the children, and pass a sort expression to that preftcehPath.