Hi!
There is a work about implementation of W515 GENBOD generator and user defined cross sections from EXFOR database.
I think for your purpose you need to implement this generator because you have products from your reaction and this generator should help. It produces the products taking into account energy conservation.
If you are don’t interested in secondaries particles from your reaction and you just need the statistics about how much reactions occurs for example then the task is easier. You only need to create some additional module to take into account external cross sections. Please find the example about implementation of this here: