Backend edit of date-based discount price set contribution

We use data based price sets to offer 3 periods of early bird event registration. For every period the base price is a one item radio button which is selected by default (see attached picture).

Sometimes a parent registered for the wrong camp or would like to pay with a different payment processor AFTER the early bird period has been passed and we need to edit of records a new contribution with the price of the already passsed period.

In these and some other situations we would like to be able to be able to edit the event contribution from the backend and override the date-based part of the price set. Of course only admins should be able to do that, but it would help us out a lot in the not so common situations that happen every year.

Probably the easiest solution would be to be able to expose all date-based price set items in the backend and show them as checkboxes. But maybe there is even a simpler solution to this.