I still think a Dutch company is most likely, and Nederlandsche Fotografische Industrie N.V. literally means it's calling itself the Dutch Photographic Industry.
The 1920's and 30's were a time of major change in the photographic industries, we see many mergers in Europe, we also see new coating plants being set up so it's entirely possible the Dalco trade name come from a smaller company that merged or joined the Nederlandsche Fotografische Industrie N.V.
We see this happening in the UK where companies merge to form APM, and APEM (Amalgamated of Photographic Materials Ltd - the coating plants, and Amalgamation of Photographic Equipment Manufacturers - the camera and equipment side of the came group). Ilford is gradually absorbing smaller competitors but there's still new coating companies emerging as the recession begins to lift.
Ian