Use something like this to get the first of the month three months ago (prompt 1):
Date(Year(DateAdd('m', CurrentDate, -3)), Month(DateAdd('m', CurrentDate, -3)), 1)
Use this to get the 11th day of the next month (prompt 2):
Date(Year(DateAdd('m', CurrentDate, 1)), Month(DateAdd('m', CurrentDate, 1)), 11)
Use this to get the last day of the next month (prompt 3):
Date(Year(DateAdd('m', CurrentDate, 2)), Month(DateAdd('m', CurrentDate, 2)), 1) -1
So, your selection formula would look like this:
(
{Del_Date} in [Date(Year(DateAdd('m', CurrentDate, -3)), Month(DateAdd('m', CurrentDate, -3)), 1) to
Date(Year(DateAdd('m', CurrentDate, 1)), Month(DateAdd('m', CurrentDate, 1)), 11)] or
(
{customer} = 'XXX' and
{DelDate} <= Date(Year(DateAdd('m', CurrentDate, 2)), Month(DateAdd('m', CurrentDate, 2)), 1) -1
)
)
I added extra parentheses around the whole thing in case you have additional selection criteria.
-Dell