They weren't very happy when Dutch brewers proposed weakening their beer:
The second unpleasant point, that the German authorities objected to a further reduction in the gravity of the Dutch beer, partly in connection with the claims of the German armed forces."
Minutes of the management of the CBK on 26th March 1941, held at the Amsterdam City Archives, document number 31121-1, page 228.
The Wehrmacht, quite predictably, wanted full-strength beer for its troops. Though they wouldn't be able to demand that forever as the food supply situation worsened in occupied Europe.
The plan was to distribute beer to German cantines centrally, through the Meelcentrale (an organisation dedicated to distributing grain) and the CBK (the brewers' organisation:
"6. Deliveries to the German Wehrmacht, Survey regional beer turnover.
With regard to the deliveries to the German armed forces, it was promised that these would be made on the basis of a distribution by the Meelcentrale via the C.B.K. The same system is applied in Germany in the distribution of beer requirements for the German armed forces in Poland, which are distributed among the German breweries by the Ersatz Verpflegungs Magazin (E.V.M.), without taking into account preferences for certain beer brands.
The N.M.C. already provided a similar distribution for several other articles in the Netherlands. With regard to the practical application of this, it is still necessary to speak with Dr. Engelhard. Meanwhile, the C.B.K. a survey will be set up to find out approximately how large the beer consumption of the German soldiers is. In connection with this, a survey is held at 16 breweries, together representing + 85% of the total Dutch turnover, to get an impression of the regional sales of the beer. The speaker is convinced that this survey will provide a great deal of work for the breweries concerned. The Meelcentrale originally wanted a survey into the turnover of the +- 30,000 pubs in the Netherlands, in which case the amount of beer consumed by the German military would also have to be stated. The speaker replied that such a survey was practically impossible to carry out, if only because many pubs do not keep accounts at all. The speaker continued that the idea occurred to the chairman and secretary to link the problem of supplying the German armed forces with redistribution. There is still the difference of opinion between export breweries which have large stocks and breweries with relatively little stock. A leveling of supplies can be achieved if the breweries with the largest stocks deliver the beer to the canteens; for this they receive extra brewing rights, but no extra raw materials. This point will require further discussion."
Minutes of the management of the CBK on 26th March 1941, held at the Amsterdam City Archives, document number 31121-1, page 230.
One of the problems in working out how much German troops consumed, was that they didn't limit their drinking to military canteens, but also drank in normal pubs. Pretty complicated, as you'd need information from every one of the 30,000 pubs in the country. It would also depend on publicans keeping track of what was drunk by soldiers and what by civilians.
Central distribution of beer for German canteens had one huge potential danger. It meant that the CBK would know exactly where each German canteen was and how much beer they required per month. Which meant they'd know the size and disposition of all the German military in the country. Very handy information for the Allies.
As I've already posted, someone at the CBK did, indeed, pass the data on to Allied spies.