Darling, the Girls’ Amateur champion from Broomieknowe, had an up-and-down day, carding seven birdies and six bogeys, as she signed for a 72, which left her sitting in a tie for 15th in the battle to make the top 64 and ties after two rounds.
North Berwick’s Grace Crawford, who followed in Darling’s footsteps by winning the R&A Girls’ Under-16 Championship earlier in the year, was next best among the Scottish contingent with a 73 that contained four birdies.
Jasmine Mackintosh (Murcar Links) opened with a 74, one better than both West Kilbride’s Duncan, who landed the title at Kilmarnock (Barassie) last year, and Aboyne’s Carmen Griffiths.
Duncan, the leading amateur in last year’s AIG Women’s Open at Carnoustie, started with a bogey before dropping two shots in the closing four holes.
England’s Esme Hamilton carded a best-of-the-day 68 to lead by one from compatriot Amelia Jane Williamson, as well as Italian duo Emilie Alba Paltrinieri and Alessandra Fanali.
Meanwhile, the Scottish Senior Women’s Open gets underway on Tuesday, with 82 golfers teeing up at Stranraer.
Mortonhall’s Karen Ferguson-Sneddon came out on top last year at Aberdour, beating Iona McKean 2&1 in the final.
In the men’s ranks, Jack McDonald, who plays at Schoss Roxburghe Hotel at Kelso, won the Tennant Cup staged at Gailes Links and Killermont.
Posting rounds of 72-72-68-70 for a level-par total, he finished a shot ahead of Carnoustie’s Scott Mann.