how to pass effects with to a target

I'm using Advanced Effects & Better Combat Effects, and I'm trying to create a ranged weapon that forces a target to roll concentration at disadvantage on a hit.

The furthest I've gotten is making a custom effect called "DAconcentration; DISSAV: concentration" and made an effect tied to the weapon "SDMGADDT: DAconcentration"

The best that happens here is that the effect to roll concentration at disadvantage is given to a target on damage, but isn't triggered by the damage that passes the effect over.

Does anyone know the code?

You would need to apply the disadvantage to the saving throw before applying the damage since the damage here is being passed before the effect; so there's no damage for the disadvantage to be triggered by. I haven't delved into the depths of this extension but if you can pass an effect following damage then I assume you can pass one on the attack roll.

Thank you for giving this a look over. the best I could ultimately do is add Kit'n'Kaboodle and turn the effect into a button on the Actions tab. just 1 button