Do the pushing effects of the Battle Master fighter's Pushing Attack maneuver and the Swords bard's Mobile Flourish stack on the same attack?

Question

Do the pushing effects of the Battle Master fighter's Pushing Attack maneuver and the College of Swords bard's Mobile Flourish stack on the same attack?

Assuming the target fails the Strength save against Pushing Attack, is the creature pushed a minimum of 20 feet away from you (plus the result on your Bardic Inspiration die), stacking both effects? Or does it only push the creature the farthest distance of the two (15 feet in this case, or potentially up to 17 feet if you have a d12 Bardic Inspiration die)?

Answer 1

These would stack.

The Dungeon Master's Guide contains a rule for combining game effects (p. 252; emphasis mine):

Different game features can affect a target at the same time. But when two or more game features have the same name, only the effects of one of them—the most potent one—apply while the durations of the effects overlap. [...] Game features include spells, class features, feats, racial traits, monster abilities, and magic items.

Because the Battle Master fighter's Pushing Attack maneuver from the Combat Superiority feature (PHB, p. 73-74) and the College of Swords bard's Mobile Flourish from the Blade Flourish feature (XGtE, p. 15) are different features with different names, they are not subject to the "most potent effect only" rule. As the DMG states, different game features can affect a target at the same time, so the effects of Pushing Attack and Mobile Flourish would stack.