Building a quick app here to update weekly progress. The date ranges are every Monday - Friday. I use this to determine the dates:
SortByColumns(
With({ withList:
ForAll(Sequence(21,-20,1) As DD,
DateAdd( DateAdd(Today(), -Weekday(Today(), StartOfWeek.Monday) +1), 4 * DD.Value , TimeUnit.Days)
)},
AddColumns(withList, "WeekEnd", DateAdd(Value, 5, TimeUnit.Days), "Week Display", Value & " to " & DateAdd(Value, 4, TimeUnit.Days))
),"Value",SortOrder.Descending)
Seems to work well to display them as it looks here:

Two issues:
When I update to the Sharepoint list, the first date (Monday) is the date that sends. Not a huge deal, but somehow struggling to send it even as just a text to display, but then that won't sort properly, so I think I am ok with this being the case with one date.
The second issue is my larger question. How do I get this to pull the date when I am in edit mode. When I am in read mode, it looks like this below and includes the first date which matches SharePoint:

In edit, it is defaulting to nothing and I cannot figure out what to put in defaultselecteditems to get this to populate corectly.

Any help would be greatly appreciated!