Add custom fields to subscriptions/subscribers

I have some custom fields that I need to display in the back end subscribers/subscriptions forms that currently do not show. Could you please add this feature to future versions, It could be included in the custom fields setup the same way as the "display in membership list" and "display on renewal" option are done. This would allow us to manage the membership with custom field information.

I thought they did show but only those common to all plans. That is the issue, we need to be able to have fields which are unique to plans and still show via admin screens.