I agree with the above, leave a note on rainmaker and see if they just fix it.

If they don't, send an email to the payroll group and alpa. If that still doesn't fix it, fill out a pilot issue form.

If all they're doing is adding flying on day 1 with no other changes, there is no way that the "displaced period" could stretch into other days then it's completely shenanigans but as someone mentioned it could just be a coding issue.

If you're displaced on all days of the trip then you'll need to look at the examples in LOA 67 to determine which flights should have been allocated to which days.