web service deep insert Business central cloud

hello everyone,

I am using cloud Business central. I am trying to post the Sales header and sales lines In one API request. this is below what have done so far

I created the web service from sales order page 42

second, I used the following request, with the “expand” parameter



the post request is going with our errors, but no lines are created. though

get request is working fine and retrieve header and lines,