Let F q be the finite field with q elements and let N be the set of non-negative integers. A flag of linear codes, where C ⊥ i denotes the dual code of the code C i . Consider F a function field over F q , and let P and Q 1 , . . . , Q t be rational places in F. Let the divisor D be the sum of pairwise different places of F such that P, Q 1 , . . . , Q t are not in supp(D), and let G β be the divisor t i=1 β i Q i , for given β ′ i s ∈ Z. For suitable values of β ′ i s in Z and varying an integer a we investigate the existence of isometry-dual flags of codes in the families of many-point algebraic geometry codes