Possibility to attach a Document to future transactions [Edited]

Valderi

It would be interesting to be able to attach a document to future transactions in Bills & Incomes

UKR

If this future transaction is the next instance of a Scheduled Reminder, you can do so now. Simply record the future dated transaction reminder into your register now, then attach the document to the register transaction.

NotACPA

Restating @UKR's response … it appears that you can't attach a document to a transaction that hasn't been recorded, one that's only scheduled.

Seems reasonable to me.