CDK: Add origin/behavior to existing CloudFront distribution

We have a CF distribution that is used for caching responses from MediaPackage. We have multiple MediaPackage endpoints and for each endpoint there is a corresponding origin/behavior on the same CF distribution.

Using CDK how can we add a new origin/behavior on the existing CF distribution?. I tried below but ran into an error:

        // load existing distribution
        const distribution = Distribution.fromDistributionAttributes(scope, `${props.stackName}-Distribution`, {
            distributionId: 'E33333B',
            domainName: 'test.example.com'
        }) as Distribution;

        // Convert to CfnDistribution
        const distributionLive = distribution.node.defaultChild as CfnDistribution;
        const distributionConfig =
            distributionLive.distributionConfig as CfnDistribution.DistributionConfigProperty;
        
        // Fetch origin/behaviors list
        const cacheBehaviors = distributionConfig.cacheBehaviors as CfnDistribution.CacheBehaviorProperty[];
        const origins = distributionConfig.origins as CfnDistribution.OriginProperty[];

       // Add new origin/behavior
       origins.push({..})
       cacheBehaviors.push({..})

Error:

/dist/lib/resources/cloudfront.js:95
        const distConfig = distributionLive.distributionConfig;
                                                   ^

TypeError: Cannot read property 'distributionConfig' of undefined