Hi @Larry Stanaland,
Welcome to the Community.
To automate sending Slack messages and their replies to Google Sheets and link them, create one Zap to log new channel messages and another to log replies, using each message's timestamp as a unique ID. Store replies in a separate sheet or tab, including the original message's identifier. Then, use Google Sheets functions like VLOOKUP or QUERY to associate replies with their corresponding messages. This method works best if each message has one reply; handling multiple replies may require a more advanced setup.
I hope this helps. Please let me know if you have any other questions or if there's anything else I can assist you with.
Hi there, @Larry Stanaland 
How did you get on with Jammer’s suggestion of using the Slack message’s ID as the value to group the replies by? Did the VLOOKUP and QUERY functions work as needed for this, or did you find a different solution? If you did we’d love to hear more about it—there could be others in the community here that are on the look out for an answer to this 
If not, feel free to share some screenshots of where you’re at with the current set up of the Zap and we’ll be happy to take a closer look at what tweaks might be needed to get it working.
Looking forward to hearing from you! 