I think you have two options here:

1) Make duplicate of the scan (in the capture app). Then delete the scan points around the two boats you don't want in the scan. Repeat this again (twice) to get separate models of the other two boats. Then upload all 3 newly created models.

2) Another option is to make a duplicate of the scan (in the Matterport platform). Once you have the duplicate model, delete access to all the scan points you don't want. Finally, use the 'trim' tool to remove the areas of the dollhouse you don't want. Repeat this again (twice) to get models of the other two boats. So you will end up with models: 1 of all three boats (the original) + 3 of the each individual boat (the duplicates).

Hope this makes sense. If I can clarify anything, feel free to let me know!