Extract personIdExternal from EC and use result for query for request-reply

Hi,

I have a requirement where I need to extract all personIdExternal. I have done this by calling SF using SF adapter and used perPerson entity and selecting only personIdExternal. After this, I need to use the list of personIdExternal to query LMS SF. How can I use the personIdExternal that were extracted on first step into the query for my 2nd channel? I think I saw one post here that says to split them then use the split payload, then merge them again.

Thanks.

Edit: I found the link:

https://answers.sap.com/questions/278836/hci-synchronous-split.html

Can this work in my requirement? Also, how can I use the poid that I added thru content modifier in my channel?