Do you know if the Stokke Crusi is compatible with the Maxi Cosi car seat via an adapter?
Stokke does not support other than the Stokke Izi Go ar seat to be attached to the Crusi frame because of the pram being a single-to-double = compatible with a second seat.
According to the Stokke official website, "Car seat adapters, such as those available for the Stokke® Xplory® stroller, are not available for the Stokke® Crusi stroller. The reason for this is that the car seat brands which are compatible with Stokke® car seat adapters have harnesses exposed at the back side. This would present a safety concern when such a car seat is used in the sibling configuration of the Stokke® Crusi stroller, as the child seated in the lower seat could grab on to the car seat harness."
I mean, the Crusi should be compatible with the Stokke Trailz Maxi-Cosi/Cybex-style set of adapters (try at stokke.com, at Stokke retailers, or on eBay and similar marketplaces), but it might be a safety concern and it is advisable to use the Stokke IZI Go and IZISleep car seat solution.