Custom Column based in Aggregated Data after Grouping

[LGQ]

Hello! Is there a way to  create an IF/THEN function that reads from the aggregated data  nested in each row after grouping by certain column?

I grouped by TRACKER  and inserted an index that counts the value appearance over time. I want Power Query to locate the largest number in the index column and assign a classification to it, leaving the rest with another text ("CLOSED" and "OPEN").

As an alternative I then  expanded and merged the TRACKER and INDEX columns but haven´t found the way to classify it.

Any suggestions are welcome, Thank you!!

[wdx223_Daniel]

=Table.Combine(Table.TransformColumns(#"Grouped Rows",{"COUNT TRACKER",each Table.CombineColumns(Table.AddIndexColumn(_,"idx",1),{"TRACKER INDEX KEY","idx"},each _{0}&Text.From(_{1}),"TRACKER INDEX KEY")})[COUNT TRACKER])