What happens if you Brush a Brush?

If you use an ability (such as Green Father's) to replace a Brush battlefield token with another Brush battlefield token, the original Brush token ceases to exist, and the new Brush token occupies that space.

According to the RiftJudge FAQ (9356) and Rules FAQ Clarification (2026-04-29):

• Replacing a Brush: When you "Brush a Brush," the existing Brush token is replaced and ceases to exist. Because a Brush token is a battlefield, you cannot have two battlefields in the same space simultaneously; the new token simply replaces the old one.
• Swapping Back: If you later choose to "swap back" the battlefield (the triggered ability on the Brush token), you can choose to swap back to the original battlefield that was at that location before it was first turned into a Brush token. This is because the replacing object inherits the relationship with the original battlefield that it replaced, per Rule 438.1 and Rule 438.7.b.

In short: The Brush token is replaced, and when you finally decide to swap the battlefield back, you revert to the original physical battlefield card that was there before any Brush tokens were created at that location.