You can find what structures (KIT's) a specific part is included in by selecting 'Structures this product is included in' found in the context menu.
This opens a list of articles with structures where the specific part is included.
Notice the list will the structures with a valid version (status=4).
If you need to see structures with version statuses that are for example 'waiting approval' (status =2) or in an edit version (status=1) you can easily change the st:4 to another status or enter the filter and choose to see the specific version status you require.
If you choose 'All version statuses', this will list all structures the part has been included in.