Lambda MAP combined with HSTACK

Thanks to both, I know this is not the same but it is why I wanted to put the Hstack where I did , this does work;;

=LET( n, E4:E16,it,F4:F16, f, H4:H6, REDUCE(E3:F3, f, LAMBDA(x,y,VSTACK( x, IFNA( HSTACK( y, UNIQUE( FILTER(it,n = y ))),y)))))


but this does not have a sum or if

Richard.