Head coach Rhodri Thomas felt his side “should have won” as they let a 12-point half-time lead slip at Livingston on Saturday.
The Reds handed a recall to Charlie Hamilton in the second row and Kyle Hamilton replaced the injured Ian Watt at centre.
Stalwart Graeme Dykes returned to the 1st XV squad for the first time since converting from the centre to the back row.
Jack Hamilton, an ever-present since joining the club early in the season, scored a sublime solo effort after chipping the Livi defence, before re-gathering to dive over under the posts.
His half-back colleague Gareth Pritchard made no mistake with the extras, and he was on target again as he converted the visitors’ second try, from full-back James Ferguson.
He got on the end of a well-worked team move to go over, while the visitors were dominant at the set-piece and skipper Colin Stuart led the defensive effort.
South African Pritchard landed a penalty to extend the Reds’ lead, and despite the hosts crossing for their first try of the afternoon, the county side held a comfortable advantage at the half-way point.
The second half saw Livingston slow the ball down and prevent the Reds from getting on top as they had done in the opening 40 minutes.
Livi skipper John Bruton contributed 10 points as he scored a try, penalty and conversion from scrum-half in their comeback win, while prop Lewis Cantley crossed for the decisive score.
He sneaked through a gap in the Haddington defence to go over and ensure defeat at the West Lothian venue for a third year in succession.
A disappointed Thomas said post-match: “This was another disappointing result for us and a game we should have won.
“We put ourselves into a good position at half-time with a decent lead.
“But unfortunately we were unable to add to our score throughout the second half and allowed Livingston back into it.”
The Reds, without a league fixture, will continue their long-running trip to CYM in Dublin, with the annual Friendship Cup match to be played tomorrow (Friday).
West of Scotland visit Neilson Park next Saturday (March 26).
The head coach added: “We will put this result behind us and start preparing for a difficult challenge against West.”

Haddington: James Ferguson, Kyle Adams, Kyle Hamilton, Liam Clutton, Mark Robertson, Gareth Pritchard, Jack Hamilton; Michael Dunlop, Colin Stuart CAPTAIN, Garry Cockburn, Ben Laing, Charlie Hamilton, Jonny Riddell, Kris Paterson, Mark Renton
Replacements: Alex Cunningham, Phill Smith, Graeme Dykes, Andrew Durkin (unused)