I have a workflow which runs a DAX query against a Power BI report and returns results in a JSON array. This array has 4 null values that a later step in my workflow does not like and honestly the output will look better by replacing them as well.
Below is a partial snippet of the JSON output. As I mentioned you can see 2 of the nulls here, 1 for Broad LOB and 1 for Marketing Segments. The other 2 are further down in the array and both are nulls for the marketing segment, but in the case of those 2 the rows do have populated Broad LOB values.
{"results": [{"tables": [{"rows": [{"Mart Policy Term[Broad LOB]": null,"Mart Policy Term[Marketing Segments]": null, This is what the output looks like as is
And here is what I would like it to look like

I have initialized 4 variables which each include the string value I want to use as a replacement, "Overall", "Total", "PL-Total" and "CL-Total". I think the next step is a select action using the JSON output but I feel like it is only giving me the option to select all Broad LOB's or Marketing Segments and I only want to replace the ones that are Null. How do I key on the specific Null Broad LOB and null Marketing segments an ensure each gets replaced with the correct variable?
Update 1: As per the usual as soon as I ask my brain kicks in and now I am wondering if I can use a condition to check for Broad LOB is null or Marketing Segment is Personal Lines and Broad LOB is null to make sure it replaces the specific instances as needed. Does this make sense?