How did you came to know this Extending steps , Did you try creating Custom field like this​ ?Please provide any pointer / steps to introduce and custom composite multi in my custom meta data schema.

Yes. Thanks - I used PageManager().touch(); Soved the purpose. Thank you all

is it OK to set the "cq:lastModified"  property? If i can set this I am get the trigger. Please suggest.

Thanks but as update, I had already created a custom roll-out following the same Links - it is working for case of updating page from Site Admin or Page Manger.   But when we modify page property through Sling API. There is not trigger(Modify) hence it is not reaching my Custom Action.

I have a similar requirement and created a custom LiveActionFactory and created a Custom Rollout configuration with Trigger as Modify and it is working fine when I modify my Pages from Site admin. But In addition to that, my blue print pages will be created, update or modified  from a back job. So I...