Including ISR In Collisions

Hi everyone,

I'm doing a summer project looking at linear colliders and what the kinematics of the final state particles may look like when using a BSM model compared to the SM.
My process that I'm studying is the e+ e- > z > h z with the higgs turning into b b~ and the z turning into leptons. But I also want to include ISR processes in this too, so ideally I want either the electron or positron to emit a photon before colliding. However when I try to do this in MadGraph I get nonsensical Feynman diagrams when I try and run the process: e+ e- > z > h z a. Because this process would imply that the photon is given off after the z boson is created, when in fact I want it before.
I don't know how to format the generate command correctly for ISR processes, so could anyone shed some light on how to do it.

Many thanks in advance :)