For each isomer enumerate all paths in each isomer graph (i.e the total number of single bonds, two adjacent bonds and so on) according to the Randić definition:
Book chapter nr. 7 "Partial Ordering" and references therein in "Solved and Unsolved Problems of Structural Chemistry" by Milan Randić, Marjana Novič and Dejan Plavšić, CRC Press (2016), https://doi.org/10.1201/b19046