Hi Jonel, for flatted chords, do you mean the root is flattened or the third? For the root you can type a "b" next to the chord and for the third it works if you write it as a minor chord, like Am.

It's been a long time since I had to think about borrowed chords! I know in classical music they're typically written with a slash between two Roman Numerals, like V/V, or ii/V. Band-in-a-Box does not recognize this type of input. Using slashes instead specifies the root of the chord, such as C7/G. In this example, the G will be in root position of the C7 chord.

As you mentioned, the best way to enter these chords is to think of the actual chord that is being entered. For example, if you are in A Major, then the V/V chord is actually the B Maj chord. I can pass along the idea to our developers to add borrowed chords. However, this might be tricky to program in, since Band-in-a-Box already has a function that utilizes slashes and this could cause confusing in the programming. This is just speculation though as I am not a developer.

Best,
Chantelle