Group Lambda Logs

Unfortunately, it would be difficult to combine the logs of multiple Lambda functions in one log group.
As described in the following document, the log group is defined as "/aws/lambda/<YourLambdaFunctionName>" and it does not seem to be possible to change this.
https://docs.aws.amazon.com/prescriptive-guidance/latest/implementing-logging-monitoring-cloudwatch/lambda-logging-metrics.html#lambda-function-logging

Lambda automatically creates a log group when your Lambda function is first invoked. Lambda functions can have multiple versions and you can choose the version that you want to run. All logs for the Lambda function's invocations are stored in the same log group. The name cannot be changed and is in the /aws/lambda/<YourLambdaFunctionName> format. A separate log stream is created in the log group for each Lambda function instance. Lambda has a standard naming convention for log streams that uses a YYYY/MM/DD/[<FunctionVersion>]<InstanceId> format. The InstanceId is generated by AWS to identify the Lambda function instance.