StepFunction - to create array in resultselector

I am trying to create a payload definition that should look like - in 1st step which is new tasks.LambdaInvoke

 "StepResult":[
	  "Step1":{				
		"Status" : "Success"
		"Errors": "[{}]",	
		"Message": "Count is 0"
		"StartTimeUTC":
		"EndTimeUTC": 
	  }]

after which i have next step which will invoke an activity - new tasks.StepFunctionsInvokeActivity this also will generate a payload, but I am trying to append that to the step result back, meaning now my step result will have 2 steps which should look like - "StepResult":[ "Step1":{ "Status" : "Success" "Errors": "[{}]", "Message": "Count is 0" "StartTimeUTC": "EndTimeUTC": } "Step2": { "Status": "Success", "Errors": "[{}]", "Message": "Successfully transferred entity'" "StartTimeUTC": "EndTimeUTC": } ]

Can yo help me how can we achieve this using typescript cdk