Bb Chord Progressions: Relative Minor Substitutions

Remember from last time:

I. Bb major
ii. Cm
iii. Dm
IV. Eb major
V. F major
vi. Gm
vii(b5). Adim

Each major chord in the key of Bb has a relative minor that might sound great instead of playing the major chord, and vice versa. What? In other words...

I/vi: Bb major could possibly be substituted with Gm
IV/ii: Eb major could possibly be substituted with Cm
V/iii: F major could possibly be substituted with Dm

Instead of playing I-V-IV-I, for instance, try the following permutations (not an exhaustive list), but we'll start with the original progression:

I-V-IV-I: Bb F Eb Bb
I-iii-IV-vi: Bb Dm Eb Gm
I-V-ii-I: Bb F Cm Bb
vi-V-IV-I: Gm F Eb Bb
vi-iii-ii-vi: Gm Dm Cm Gm
etc.

Substituting a major chord with its relative minor (and vice versa) might liven up a boring progression with a less boring progression (albeit still widely used).