Having traveled quite a bit in the Baltics, my understanding from multiple EXP agents over the years is that Flybe operated flights are not bookable as awards. On occasion, you will find a city with both Flybe and mainline AY service, so hopefully you can find an AY operated option, though often none exists. It is disappointing to do an award redemption and then need to toss out $300-$500 or more on top of it to finish the segments the award won't allow due to this issue with Flybe.