How to concatenate two document lists in a webMethods flow service?

I have sequence of two steps. In both of them I get some data from sql database and trying to save them in document list.

only problem is that when the second step of sequence is executing it override my document list instead of adding new elements.

to make it clear I want on my list: seq1 elements + s2 elements

but i get only s2 elements.

You can use the WmPublic service pub.list:appendToDocumentList to construct a new list which is a concatenation of your two lists.

Call pub.list:appendToDocumentList, passing your seq1 list as the toList input argument and your s2 list as the fromList input argument, and the service will return a new list called toList which is a concatenation of seq1 and s2.