Heathfield pulled off an Intermediate Cup shock and helped new coach Herb Merritt get one up on his younger brother.
The Sussex One outfit came from 8-3 down in the final quarter to win 11-8 away to a Brighton side coached by Bert Merritt.
Both brothers took over in the summer, Herb switching from Worthing's colts section and Bert moving down a division from Effingham and Leatherhead.
Julian Wates powered over for a 65th minute try, then Lewis Beale, who had a mixed day, with the boot, added his second penalty to settle matters, but Herb insisted: "We have still got a long way to go.
"This will give our youngsters more confidence. I looked upon the match as our last trial of the year. We played certain tactics and they worked.
"That was what mattered. The fact that the coaches were brothers had nothing to do with it."
Even delighted Heathfield will concede the result was more memorable than the match itself, which was packed with individual errors, especially from Brighton.
The highlight was a fabulous 60-yard solo try from home scrum half Julian Hutchens after Tudor Ellis had taken a strike against the head. Geraint Jones added a penalty.
Ellis was later sin-binned for throwing the most visible punch in a late skirmish.
Bert Merritt admitted his side made too many basic errors and added: "The team looked very rusty. We handed it to them and they took advantage of our mistakes.
"I can't see any major problem. We just did some dumb things."
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article