How to merge lists in Business Process

Hello,

I have a method in an operation wich return a list of %String (listId).
I call it multiple time in a Business Process and want to have all the lists I get put into one.
Not having "set context.listIdProcess = callresponse.listId" , but a way to add the elements of listId in context.listIdProcess.

There is an other way than append each element of the list?

Thanks for yours answers,

Corentin