I assume that you've tried simply filtering by the date in the 'Order' relationship (TO), and any other 'obvious' filters?
Here's a way that works for me. It's ugly and could be refined, I'm sure, but it proves the principle.
Define a global date field, gDatetoFilter in OrderDetail. Create a calculation field of OrderDate in OrderDetail
OrderDateDetail = Order::OrderDate
Put the gDatetoFilter field on the Customer layout. Set the portal to filter by that date (eg: OrderDetail::OrderDate > gDateToFilter)
Note that you will have to force a screen re-draw if you change the global filter date.
I'm sure that can be refined greatly.
My plan is this solution also. Will the calculation field slow down the performance, if the OrderDetail records will be a lots?
Just try it. You can create a parent-child combo test file and import as many records into the child table that you think you'll have to accommodate, and then some more. I think you'll be pleasantly surprised hope efficiently FM handles it.