The relationship between aid and trade from the 1970's to 2014 is discussed extensively in the IOB report 'Good things happen to those who make them happen'. A Dutch Advisory Council on International Affairs report in 2013 already concluded 'that it not impossible to give Dutch business a role in aid, provided that the objectives of development cooperation prevailed'.
Untying aid is not necessarily a solution to promote bilateral trade relations, that are an important goal of private sector development initiatives supported through ODA for development related activities.
https://www.adviesraadinternationalevraagstukken.nl/documenten/publicaties/2013/02/01/wisselwerking-tussen-actoren-in-internationale-samenwerking
https://www.iob-evaluatie.nl/publicaties/rapporten/2014/04/01/392---iob-study-good-things-come-to-those-who-make-them-happen-return-on-aid-for-dutch-exports
https://www.iob-evaluatie.nl/resultaten/integratie-nederlandse-hulp