This is one method, using Price/discount agreement journals.
Create a new price discount agreement journal, and open the Lines. On the Lines form, click 'Select'.
On the 'Select criteria to filter...' form, tick 'Line discounts'.
Next to 'Customers', choose 'Group'. The 'Group type' should change to 'Line discount group'. Enter the name of the line discount group into the Relation field. Untick 'Include additional references'.
Next to 'Items', choose 'All'.
Click 'Select'. AX will populate the journal with 10,000+ lines.
Choose 'Copy and revise'. Tick 'To date', and enter 31/12/2016 as the 'To date'. Click 'OK'.
You now have 20,000+ lines!
Post the journal.
Create second new price discount agreement journal, and open the Lines. As before, on the Lines form, click 'Select'.
On the 'Select criteria to filter...' form, choose the same criteria as before. AX will populate the journal with 20,000+ lines.
Highlight a line with To date of '31/12/2016'. Right click on the To date, and choose 'Filter by selection'. AX will show 10,000+ lines. Use Ctrl+A to select them all. Press Alt+F9 to delete them all from the journal.
Clear the filter. AX will show 10,000+ lines, all with a 'To date' of '31/12/2015'. Click the button 'Select all agreements to...'. This will mark all these lines for deletion. Post the journal.
You now have 10,000+ active T/A lines for that line discount group, and all of them have a To date of 31/12/2016.
