Example

     var sssss = await _managerPlatformDataService.GetPlatformData();
 
            var acvite = sssss.Single(x => x.IsActive && x.Code == AMZEU.ToString()).Marketplaces;
 
            foreach (var Channel in partnerPlatformsResponse?.PartnerChannels)
            {
                var marketplaceCodes = Channel.PartnerMarketplaces.Select(m => m.CountryCode);
 
                var missingMarketplaceResponseDtos = acvite
                    .ExceptBy(marketplaceCodes, m => m.CountryCode)
                    .Select(m => new PDto(new PM
                    {
                        Marketplace = m,
                        PartnerChannelId = Channel.Id
                    })
                    { IsAvailable = false });
 
                Channel.PartnerMarketplaces = Channel.PartnerMarketplaces
                    .Concat(missingMarketplaceResponseDtos)
                    .OrderBy(x => _orderOfMarkets.IndexOf(x.CountryCode))
                    .ToList();
            }