D365 Plugin: trigger when a marketing list added on Campaign entity

Hi,

I'm trying to trigger my plugin when a marketing list is added on a campaign.

First, I tried Associate.I can go into my code but I can't get RelatedEntities in plugin context.

Then,I tried AddItem.It's weird that it can't be triggered when I add a marketing list on campaign,but It can be triggered when I add a campaign on marketing list.

Any help on this is appreciated.THANKS.