I have a fairly complex scenario and I need to ensure items I have in a list are sorted.

Firstly the items in the list are based on a struct that contains a sub struct.

For example:

public struct topLevelItem
{
 public custStruct subLevelItem;
}

public struct custStruct
{
  public string DeliveryTime;
}

Now I have a list comprised of topLevelItems for example:

var items = new List<topLevelItem>();

I need a way to sort on the DeliveryTime ASC. What also adds to the complexity is that the DeliveryTime field is a string. Since these structs are part of a reusable API, I can't modify that field to a DateTime, neither can I implement IComparable in the topLevelItem class.

Any ideas how this can be done?

Thank you