If you would like to create a Discount especially for a Day Seats or 'Rush' offer (i.e. via TodayTix), then the best option is to create an Availability Status that is tied to a Discount.
Here you can then choose the seats that the Discount will work for, both on the Availability Status itself and per Performance via the Box Office page.
Learn more - Guide: Rush Tickets
Discount
Create a Discount
Add the Discount to your Event's Price Table(s). Make sure to add Adjusters if needed
Availability Status
Go to the Availability tab on your Event and select the Venue Plan you want to set the Status on
Create a new Availability Status - select your seats, the correct Channel(s) (e.g. TodayTix, Website) and an Activation Schedule if you wish
NOTE - you can amend the seats you'd like to use for this offer/Status per Performance once you've created the Status.
Attach the Discount you want to add to your seats. This will mean the seats won't be available for the Channels you've chosen until the Discount is applied
Click Save Availability Status
Online Booking Flow example - seats when locked to a Discount with an Availability Status:
Learn more - Guide: Create & Manage an Availability Status
Apply Availability Status to Performances
Select the Performances tab on your Event
Use the Filter and Action bars to add the Availability Status to the correct Performances
NOTE - this will mean every Performance will have the same seats attached. If you'd like to adjust the seats per Performance, you can do this from the Box Office page.
Learn more - Guide: Change Seat Availability in Box Office