Recursive lambda

JeteMc answered the original Q. GregB11 made the first O365-type formula:

https://www.excelforum.com/excel-for...ml#post5919354



I took it to the next stage. However, as I said in the thread, my brain only works in straight lines. I can't do recursive lambdas. The original post referred to thousands of staff memebrs and 15 reporting levels. Can anyone out there see how to calculate the number of direct and indirect reportees under each staff member with a recursive lambda, or similar, thus avoiding the need for 15 of these????

Level2,FILTER(a,ISNUMBER(MATCH(b,Level1,0)),"")