If I understand correctly, you want to include Bank Expenses as part of an existing transaction instead of needing to use a separate transaction.  You can do this by using the "Split Transaction" which is the button to the right of the Category entry.  It allows splitting a transaction into multiple categories.

Does this help?

Created attachment 102031 [details]
attachment-5127-0.html

Grazie per la sollecita risposta , non ci avevo pensato.

2016-11-04 16:28 GMT+01:00 Jack <bugzilla_noreply@kde.org>:

> https://bugs.kde.org/show_bug.cgi?id=372076
>
> --- Comment #1 from Jack <ostroffjh@users.sourceforge.net> ---
> If I understand correctly, you want to include Bank Expenses as part of an
> existing transaction instead of needing to use a separate transaction.
> You can
> do this by using the "Split Transaction" which is the button to the right
> of
> the Category entry.  It allows splitting a transaction into multiple
> categories.
>
> Does this help?
>
> --
> You are receiving this mail because:
> You reported the bug.

It seems that Jack helped here.