I am not great at identifying lines and I don't have clementine but here is what I did with Seafoam.
I made a mental list of the color palette then I used the tags here on the site to search for products. When I went through CHA sneaks I also looked for things that might match. Seafoam is very neutral and graphic but that isn't stopping me from adding a few floral bits or patterns that are busier because i like them .
For me the bigger thing was identifying what would NOT work IMO. Seafoam has orange so I am avoiding coral. It has aqua and teal so I am not doing olive green or mint. I have happily added bits of pink and red. I may mix in some snap and it actually does have some olive, but I probably won't use a whole card of that shade only.
Hopefully you can translate that to work for your core kit!